Martin von Zweigbergk <martinvonz@google.com> [Thu, 01 Feb 2018 08:17:11 -0800] rev 35848
testrunner: on error, color the "(case xxx)" part the same as filename
When using #testcases, the lines that read something like
ERROR: test-split.t (case obsstore-off) output changed
get colored red and the filename gets highlighted with a brighter
red. This makes it harder to notice the "case obsstore-off" part, but
it does seem important, so let's highlight it.
Differential Revision: https://phab.mercurial-scm.org/D1959
Augie Fackler <augie@google.com> [Thu, 18 Jan 2018 10:08:23 -0500] rev 35847
python3: whitelist an additional 23 passing tests
Differential Revision: https://phab.mercurial-scm.org/D1908
Augie Fackler <augie@google.com> [Thu, 18 Jan 2018 09:58:40 -0500] rev 35846
tests: fix a missed b prefix in a test extension in test-strip.t
# skip-blame just a bytes prefix
Differential Revision: https://phab.mercurial-scm.org/D1907
Augie Fackler <augie@google.com> [Thu, 18 Jan 2018 09:14:30 -0500] rev 35845
revlog: correct type in check to verify rawtext is immutable
This fixes far more failures than I feel like it has any right to, so
there's clearly some subtle interaction between self._cache and other
parts of this code. :(
Differential Revision: https://phab.mercurial-scm.org/D1906
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 22:05:37 -0500] rev 35844
mq: use bytes() instead of str() to encode statusentries for writing
Differential Revision: https://phab.mercurial-scm.org/D1903
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 22:05:02 -0500] rev 35843
mq: open status file et al in bytes mode
Differential Revision: https://phab.mercurial-scm.org/D1902
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 22:04:34 -0500] rev 35842
mq: fix up statusentry to be both repr()-able and bytes()-able
Differential Revision: https://phab.mercurial-scm.org/D1901
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 22:07:09 -0500] rev 35841
python3: whitelist another 7 passing tests
Differential Revision: https://phab.mercurial-scm.org/D1900
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 21:48:37 -0500] rev 35840
localrepo: pass transaction kwargs as strings, not bytes
Differential Revision: https://phab.mercurial-scm.org/D1899
Augie Fackler <augie@google.com> [Thu, 01 Feb 2018 12:38:04 -0800] rev 35839
localrepo: consistently use native str when __dict__ is involved
Differential Revision: https://phab.mercurial-scm.org/D1898
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 21:46:29 -0500] rev 35838
smartset: use native string when peeking in __dict__
# skip-blame just an r prefix on a string literal
Differential Revision: https://phab.mercurial-scm.org/D1897
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 21:46:09 -0500] rev 35837
obsolete: use native string when peeking in __dict__
# skip-blame just an r prefix on a few string literals
Differential Revision: https://phab.mercurial-scm.org/D1896
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 21:45:15 -0500] rev 35836
lsprof: use native string when peeking in __dict__
# skip-blame just an r prefix on a string literal
Differential Revision: https://phab.mercurial-scm.org/D1895
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 21:44:15 -0500] rev 35835
dirstate: use native strings when peeking in __dict__
# skip-blame because we're just adding a prefix on a string prefix
Differential Revision: https://phab.mercurial-scm.org/D1894
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 21:43:46 -0500] rev 35834
context: use native string when peeking in __dict__
# skip-blame because we're just adding a prefix on a string constant
Differential Revision: https://phab.mercurial-scm.org/D1893
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 21:42:56 -0500] rev 35833
bundlerepo: use native str when peeking in __dict__
# skip-blame since it's just a string constant prefix
Differential Revision: https://phab.mercurial-scm.org/D1892
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 20:41:51 -0500] rev 35832
transaction: fix hg version check when loading journal
Differential Revision: https://phab.mercurial-scm.org/D1891
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 20:38:10 -0500] rev 35831
branchmap: make error messages consistent between Python 2 and 3
Differential Revision: https://phab.mercurial-scm.org/D1890
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 20:37:17 -0500] rev 35830
tests: bytestring-ify all the adhoc extensions in test-strip.t
# skip-blame because we're just adding b''
Differential Revision: https://phab.mercurial-scm.org/D1889
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 20:09:52 -0500] rev 35829
filemerge: fix regular expression pattern to be bytes
# skip-blame just a bytes prefix
Differential Revision: https://phab.mercurial-scm.org/D1888
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 20:09:10 -0500] rev 35828
tags: explicitly grab list of dict keys
Differential Revision: https://phab.mercurial-scm.org/D1887
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 20:08:40 -0500] rev 35827
commands: replace map() with list comprehension
This will work identically on Python 2 and 3.
Differential Revision: https://phab.mercurial-scm.org/D1886
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 20:07:53 -0500] rev 35826
commands: rewrite legacy ternary operator hack using modern syntax
Differential Revision: https://phab.mercurial-scm.org/D1885
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 20:07:25 -0500] rev 35825
strip: use %d for known-int string interpolation
Differential Revision: https://phab.mercurial-scm.org/D1884
Augie Fackler <augie@google.com> [Thu, 18 Jan 2018 10:22:41 -0500] rev 35824
strip: use in-place revset formatspec instead of %-formatting ourselves
Caught by Yuya during review of D1884.
Differential Revision: https://phab.mercurial-scm.org/D1905
Augie Fackler <augie@google.com> [Wed, 17 Jan 2018 19:11:51 -0500] rev 35823
tests: get run-tests to reliably hand shellquote a string and not a bytes
Differential Revision: https://phab.mercurial-scm.org/D1883
Augie Fackler <augie@google.com> [Thu, 01 Feb 2018 14:59:38 -0500] rev 35822
revsetlang: fix a doctest example on Python 3
# skip-blame because it's just some bytes prefixes
Differential Revision: https://phab.mercurial-scm.org/D1964
Augie Fackler <augie@google.com> [Thu, 01 Feb 2018 14:28:45 -0500] rev 35821
merge with stable
Augie Fackler <raf@durin42.com> [Thu, 01 Feb 2018 14:13:41 -0500] rev 35820
Added signature for changeset
d334afc585e2
Augie Fackler <raf@durin42.com> [Thu, 01 Feb 2018 14:13:40 -0500] rev 35819
Added tag 4.5 for changeset
d334afc585e2
Augie Fackler <augie@google.com> [Thu, 01 Feb 2018 14:11:18 -0500] rev 35818
merge with i18n
Wagner Bruna <wbruna@softwareexpress.com.br> [Wed, 31 Jan 2018 19:41:34 -0200] rev 35817
i18n-pt_BR: synchronized with
373fb3f5922c
Matt Harbison <matt_harbison@yahoo.com> [Sun, 28 Jan 2018 14:08:59 -0500] rev 35816
revset: evaluate filesets against each revision for 'file()' (
issue5778)
After
f2aeff8a87b6, the fileset was evaluated to a set of files against the
working directory, and then those files were applied against each revision. The
result was nonsense. For example, `hg log -r 'file("set:exec()")'` on the
Mercurial repo listed revision 0 because it has the `hg` script, which is
currently +x. But that bit wasn't applied until revision 280 (which
'contains()' properly indicates).
This technique was borrowed from checkstatus(), which services adds(),
modifies(), and removes(), so it seems safe enough. The 'r:' case is explicitly
assigned to wdirrev, freeing up rev=None to mean "re-evaluate at each revision".
The distinction is important to avoid behavior changes with `hg log set:...`
(test-largefiles-misc.t and test-fileset-generated.t drop current log output
without this). I'm not sure what the right behavior for that is (
1fd352aa08fc
explicitly enabled this behavior for graphlog), but the day before the release
isn't the time to experiment.
Matt Harbison <matt_harbison@yahoo.com> [Wed, 31 Jan 2018 23:01:44 -0500] rev 35815
test-bookmarks-pushpull: stabilize for Windows
Anton Shestakov <av6@dwimlabs.net> [Thu, 01 Feb 2018 16:46:12 +0800] rev 35814
makefile: add Ubuntu Artful docker targets (.deb and ppa)
Artful Aardvark was released on 2017-10-19 and will be supported until 2018-07.
Boris Feld <boris.feld@octobus.net> [Wed, 31 Jan 2018 16:31:34 +0100] rev 35813
bundle2: fix the formatting of the stream part requirements
Use the same pre-encoded normalization as bundlespecs for the stream v2 part
requirements. As it touch the wire protocol, it needs to change before the
release.
This was spotted by Gregory Szorc.
Differential Revision: https://phab.mercurial-scm.org/D1950
Boris Feld <boris.feld@octobus.net> [Mon, 29 Jan 2018 10:28:10 +0100] rev 35812
streamclone: extract requirements formatting
It will be reused for the formatting of the requirements of the stream v2 part
requirement and later for the stream v2 requirements.
Differential Revision: https://phab.mercurial-scm.org/D1949
Boris Feld <boris.feld@octobus.net> [Tue, 30 Jan 2018 22:27:45 +0100] rev 35811
bookmarks: fix pushkey compatibility mode (
issue5777)
The namespace used for the compatibility mode was missing a trailing 's'.
Jun Wu <quark@fb.com> [Tue, 30 Jan 2018 20:32:48 -0800] rev 35810
lazymanifest: avoid reading uninitialized memory
I got errors running tests with clang UBSAN [1] enabled. One of them is:
```
--- test-dirstate.t
+++ test-dirstate.t.err
@@ -85,9 +85,115 @@
$ echo "[extensions]" >> .hg/hgrc
$ echo "dirstateex=../dirstateexception.py" >> .hg/hgrc
$ hg up 0
- abort: simulated error while recording dirstateupdates
- [255]
+ mercurial/cext/manifest.c:781:13: runtime error: load of value 190, which is not a valid value for type 'bool'
+ #0 0x
7f668a8cf748 in lazymanifest_diff mercurial/cext/manifest.c:781
+ #1 0x
7f6692fc1dc4 in call_function Python-2.7.11/Python/ceval.c:4350
+ .......
+ SUMMARY: UndefinedBehaviorSanitizer: invalid-bool-load mercurial/cext/manifest.c:781:13 in
+ [1]
$ hg log -r . -T '{rev}\n'
1
$ hg status
- ? a
```
While the code is not technically wrong, but switching the condition would
make clang UBSAN happy. So let's do it.
The uninitialized memory could come from, for example, `lazymanifest_copy`
allocates `self->maxlines` items but only writes the first `self->lines`
items.
[1]: https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html
Test Plan:
Run `test-dirstate.t` with UBSAN and it no longer reports the issue.
Differential Revision: https://phab.mercurial-scm.org/D1948
Martin von Zweigbergk <martinvonz@google.com> [Fri, 26 Jan 2018 11:42:47 -0800] rev 35809
unamend: fix command summary line
Before this patch, the docstring started with a newline, which led the
summary line (shown in e.g. `hg help -c`) to be blank.
Differential Revision: https://phab.mercurial-scm.org/D1943
Gregory Szorc <gregory.szorc@gmail.com> [Mon, 29 Jan 2018 13:30:29 -0800] rev 35808
configitems: traverse sections deterministically
Otherwise output can be non-deterministic if there are warnings
for multiple sections.
Differential Revision: https://phab.mercurial-scm.org/D1947
Matt Harbison <matt_harbison@yahoo.com> [Mon, 29 Jan 2018 21:42:18 -0500] rev 35807
lfs: don't require the .hglfs file to be tracked to control the policy
The .hgignore file doesn't need to be tracked, nor does the git equivalent of
this file. I'm still a little concerned about the effects of forgetting to
commit this file. But the fact that conversions maintain the hashes if only the
normal vs external storage changes, should make this less risky.
Augie Fackler <augie@google.com> [Sat, 27 Jan 2018 21:50:04 -0500] rev 35806
tests: add a pattern to fix --pure tests
Test Plan:
ran all tests with and without --pure, everything passed on gcc112.
Differential Revision: https://phab.mercurial-scm.org/D1946
Boris Feld <boris.feld@octobus.net> [Fri, 26 Jan 2018 16:01:42 +0100] rev 35805
streamclone: add a comment about non-publishing being broken with v1
This change was suggested by Gregory Szorc.
Boris Feld <boris.feld@octobus.net> [Fri, 26 Jan 2018 15:51:07 +0100] rev 35804
streamclone: move requirement update into consumev2
This change was suggested by Gregory Szorc.
Boris Feld <boris.feld@octobus.net> [Wed, 24 Jan 2018 21:44:31 +0100] rev 35803
streamclone: use readexactly when reading stream v2
Yuya Nishihara pointed out that it is safer.
Boris Feld <boris.feld@octobus.net> [Wed, 24 Jan 2018 21:37:48 +0100] rev 35802
streamclone: rename '_emit' to '_emit2' for clarity
This change was suggested by Gregory Szorc.
Yuya Nishihara <yuya@tcha.org> [Tue, 23 Jan 2018 21:14:36 +0900] rev 35801
help: do not suggest "update --clean ." to cancel uncommitted merge
Follows up
41ef02ba329b.
Matt Harbison <matt_harbison@yahoo.com> [Wed, 24 Jan 2018 22:26:28 -0500] rev 35800
minifileset: note the unsupported file pattern when raising a parse error
This was useful in debugging, because I stupidly quoted it out of habit from the
command line. This isn't a great example that clearly shows the problem, but I
don't know how to improve it. The problem *is* obvious once a complex statement
or a clearly bogus string is used.
Matt Harbison <matt_harbison@yahoo.com> [Tue, 23 Jan 2018 21:29:45 -0500] rev 35799
lfs: don't automatically exclude '.hg*' files from external tracking
The only reasons I did this in the first place was because tracking externally
seems like it would always be a mistake, and the eol extension does the same
thing. Yuya and Jun thought it might be better to not do this[1], so I'll defer
to them on this. If a problem with say, .hgtags or .hgeol does arise, it can be
added back without breaking existing repos.
[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2018-January/110371.html
Matt Harbison <matt_harbison@yahoo.com> [Tue, 23 Jan 2018 20:50:02 -0500] rev 35798
lfs: rename {oid} to {lfsoid}
Per Yuya, for consistency with {lfspointer}. It might be slightly confusing for
there to be {lfsoid} and {lfspointer.oid}. But preventing ambiguity seems more
important, and the latter is controlled by the git-lfs spec.
Matt Harbison <matt_harbison@yahoo.com> [Mon, 22 Jan 2018 17:47:40 -0500] rev 35797
lfs: rename {pointer} to {lfspointer}
Per Martin von Zweigbergk's suggestion to keep this unambiguous, for when it is
migrated to {files} and friends.
Augie Fackler <raf@durin42.com> [Mon, 22 Jan 2018 18:08:50 -0500] rev 35796
Added signature for changeset
27b6df1b5adb
Augie Fackler <raf@durin42.com> [Mon, 22 Jan 2018 18:08:49 -0500] rev 35795
Added tag 4.5-rc for changeset
27b6df1b5adb
Augie Fackler <augie@google.com> [Mon, 22 Jan 2018 17:53:02 -0500] rev 35794
merge with stable to begin 4.5 freeze
# no-check-commit because it's a clean merge
Gregory Szorc <gregory.szorc@gmail.com> [Sat, 20 Jan 2018 22:55:42 -0800] rev 35793
bundle2: increase payload part chunk size to 32kb
Bundle2 payload parts are framed chunks. Esentially, we obtain
data in equal size chunks of size `preferedchunksize` and emit those
to a generator. That generator is fed into a compressor (which can
be the no-op compressor, which just re-emits the generator). And
the output from the compressor likely goes to a file descriptor
or socket.
What this means is that small chunk sizes create more Python objects
and Python function calls than larger chunk sizes. And as we know,
Python object and function call overhead in performance sensitive
code matters (at least with CPython).
This commit increases the bundle2 part payload chunk size from 4k
to 32k. Practically speaking, this means that the chunks we feed
into a compressor (implemented in C code) or feed directly into a
file handle or socket write() are larger. It's possible the chunks
might be larger than what the receiver can handle in one logical
operation. But at that point, we're in C code, which is much more
efficient at dealing with splitting up the chunk and making multiple
function calls than Python is.
A downside to larger chunks is that the receiver has to wait for that
much data to arrive (either raw or from a decompressor) before it
can process the chunk. But 32kb still feels like a small buffer to
have to wait for. And in many cases, the client will convert from
8 read(4096) to 1 read(32768). That's happening in Python land. So
we cut down on the number of Python objects and function calls,
making the client faster as well. I don't think there are any
significant concerns to increasing the payload chunk size to 32kb.
The impact of this change on performance significant. Using `curl`
to obtain a stream clone bundle2 payload from a server on localhost
serving the mozilla-unified repository:
before: 20.78 user; 7.71 system; 80.5 MB/s
after: 13.90 user; 3.51 system; 132 MB/s
legacy: 9.72 user; 8.16 system; 132 MB/s
bundle2 stream clone generation is still more resource intensive than
legacy stream clone (that's likely because of the use of a
util.chunkbuffer). But the throughput is the same. We might
be in territory we're this is effectively a benchmark of the
networking stack or Python's syscall throughput.
From the client perspective, `hg clone -U --stream`:
before: 33.50 user; 7.95 system; 53.3 MB/s
after: 22.82 user; 7.33 system; 72.7 MB/s
legacy: 29.96 user; 7.94 system; 58.0 MB/s
And for `hg clone --stream` with a working directory update of
~230k files:
after: 119.55 user; 26.47 system; 0:57.08 wall
legacy: 126.98 user; 26.94 system; 1:05.56 wall
So, it appears that bundle2's stream clone is now definitively faster
than legacy stream clone!
Differential Revision: https://phab.mercurial-scm.org/D1932
Gregory Szorc <gregory.szorc@gmail.com> [Mon, 22 Jan 2018 12:23:47 -0800] rev 35792
bundle2: always advertise client support for stream parts
Previously, enabling of stream clone over bundle2 was a server-side
only change. And clients would only advertise bundle2 support for
stream clones if an experimental config option was set.
This situation wasn't forward compatible because in the future
(when the feature is enabled on servers by default), an old client
would send a request to the server but it wouldn't send its own
bundle2 capability support for stream parts. Servers would have to
infer that clients not sending this capability were old Mercurial
clients that only sent the capability if the feature was
explicitly enabled. Implicit and inferred behavior makes implementing
servers hard. It's much better to be explicit about client features.
We should either make the config option for bundle2 stream clones
disable the feature client-side as well (so a server doesn't see
a request from a client not advertising stream support). Or we
should always advertise stream support if a client is willing
to accept stream parts.
Since I anticipating stabilizing stream clone support in bundle2
quickly, I think it's safe to always advertise client support
in the bundle2 capabilities. So this commit changes things to
do that.
Because capabilities now vary between client and server, we had
to create variations of the variable substitutions for those
strings.
Differential Revision: https://phab.mercurial-scm.org/D1931
Gregory Szorc <gregory.szorc@gmail.com> [Mon, 22 Jan 2018 12:22:01 -0800] rev 35791
exchange: don't send stream data when server.uncompressed is set
Previously, bundle2 stream support would send out data even though
the streaming clone feature was disabled. This commit changes
the part handler to respect the server config.
Differential Revision: https://phab.mercurial-scm.org/D1930
Gregory Szorc <gregory.szorc@gmail.com> [Mon, 22 Jan 2018 12:21:15 -0800] rev 35790
bundle2: don't advertise stream bundle2 capability when feature disabled
The server.uncompressed config option can be used to disable streaming
clones. While the top-level capability to advertise streaming clone
support isn't advertised when this option is set, we were still sending
the bundle2-level capabilities advertising support for stream parts.
It makes sense to not advertise that support when streaming clones
are globally disabled.
If the structure of the new code seems a bit odd, it is because we'll
have to further tweak the behavior in commit(s) ahead.
Differential Revision: https://phab.mercurial-scm.org/D1929
Gregory Szorc <gregory.szorc@gmail.com> [Mon, 22 Jan 2018 12:19:45 -0800] rev 35789
tests: add more testing around server.uncompressed
We already have testing for server.uncompressed in test-http*.t.
However, it doesn't cover the new bundle2 use case. And, we don't
have comprehensive testing of advertised capabilities.
We add tests to test-clone-uncompressed.t that demonstrate
behavior for both legacy and bundle2 configurations.
If you look closely, the bundle2 capabilities are advertising
stream support when it isn't enabled. That's a bug.
In addition, while the client is smart enough to not request
a stream clone when the server doesn't have the feature enabled,
the getbundle wire protocol command is still sending stream
clone data. This doesn't match the behavior of the legacy
stream_out wire protocol command. That's also a bug. Tests
have been added.
While I was here, I also changed how the PID is recorded in
$DAEMON_PIDS. If we kill a process, the PID formerly in
$DAEMON_PIDS no longer exists. So we should replace that file
instead of appending to it.
Differential Revision: https://phab.mercurial-scm.org/D1928
Gregory Szorc <gregory.szorc@gmail.com> [Mon, 22 Jan 2018 12:19:49 -0800] rev 35788
bundle2: move version of stream clone into part name
I don't like having version numbers as part parameters. It means
that parts can theoretically vary wildly in their generation and
processing semantics. I think that a named part should have consistent
behavior over time. In other words, if you need to introduce new
functionality or behavior, that should be expressed by inventing
a new bundle2 part, not adding functionality to an existing part.
This commit applies this advice to the just-introduced stream clone
via bundle2 feature.
The "version" part parameter is removed. The name of the bundle2 part
is now "stream2" instead of "stream" with "version=v2".
Differential Revision: https://phab.mercurial-scm.org/D1927
Gregory Szorc <gregory.szorc@gmail.com> [Mon, 22 Jan 2018 12:12:29 -0800] rev 35787
exchange: send bundle2 stream clones uncompressed
Stream clones don't compress well. And compression undermines
a point of stream clones which is to trade significant CPU
reductions by increasing size.
Building upon our introduction of metadata to communicate bundle
information back to callers of exchange.getbundlechunks(), we add
an attribute to the bundler that communicates whether the bundle is
best left uncompressed. We return this attribute as part of the bundle
metadata. And the wire protocol honors it when determining whether
to compress the wire protocol response.
The added test demonstrates that the raw result from the wire
protocol is not compressed. It also demonstrates that the server
will serve stream responses when the feature isn't enabled. We'll
address that in another commit.
The effect of this change is that server-side CPU usage for bundle2
stream clones is significantly reduced by removing zstd compression.
For the mozilla-unified repository:
before: 37.69 user 8.01 system
after: 27.38 user 7.34 system
Assuming things are CPU bound, that ~10s reduction would translate to
faster clones on the client. zstd can decompress at >1 GB/s. So the
overhead from decompression on the client is small in the grand scheme
of things. But if zlib compression were being used, the overhead would
be much greater.
Differential Revision: https://phab.mercurial-scm.org/D1926
Gregory Szorc <gregory.szorc@gmail.com> [Mon, 22 Jan 2018 12:38:04 -0800] rev 35786
tests: update test to work with Git 2.16
It looks like Git 2.16 removed the "..." from some strings.
Glob over those characters in the test output.
Differential Revision: https://phab.mercurial-scm.org/D1935
Gregory Szorc <gregory.szorc@gmail.com> [Sat, 20 Jan 2018 13:41:57 -0800] rev 35785
exchange: return bundle info from getbundlechunks() (API)
We generally want a mechanism to pass information about the
generated bundle back to callers (in addition to the byte stream).
Ideally we would return a bundler from this function and have the
caller code to an interface. But the bundling APIs are not great
and getbundlechunks() is the best API we have for obtaining bundle
contents in a unified manner.
We change getbundlechunks() to return a dict that we can use to
communicate metadata.
We populate that dict with the bundle version number to demonstrate
some value.
.. api::
exchange.getbundlechunks() now returns a 2-tuple instead of just
an iterator.
Differential Revision: https://phab.mercurial-scm.org/D1925