view tests/test-ssh-bundle1.t @ 40326:fed697fa1734

sqlitestore: file storage backend using SQLite

This commit provides an extension which uses SQLite to store file
data (as opposed to revlogs).

As the inline documentation describes, there are still several
aspects to the extension that are incomplete. But it's a start.
The extension does support basic clone, checkout, and commit
workflows, which makes it suitable for simple use cases.

One notable missing feature is support for "bundlerepos." This is
probably responsible for the most test failures when the extension
is activated as part of the test suite.

All revision data is stored in SQLite. Data is stored as zstd
compressed chunks (default if zstd is available), zlib compressed
chunks (default if zstd is not available), or raw chunks (if
configured or if a compressed delta is not smaller than the raw
delta). This makes things very similar to revlogs.

Unlike revlogs, the extension doesn't yet enforce a limit on delta
chain length. This is an obvious limitation and should be addressed.
This is somewhat mitigated by the use of zstd, which is much faster
than zlib to decompress.

There is a dedicated table for storing deltas. Deltas are stored
by the SHA-1 hash of their uncompressed content. The "fileindex" table
has columns that reference the delta for each revision and the base
delta that delta should be applied against. A recursive SQL query
is used to resolve the delta chain along with the delta data.

By storing deltas by hash, we are able to de-duplicate delta storage!
With revlogs, the same deltas in different revlogs would result in
duplicate storage of that delta. In this scheme, inserting the
duplicate delta is a no-op and delta chains simply reference the
existing delta.

When initially implementing this extension, I did not have
content-indexed deltas and deltas could be duplicated across files
(just like revlogs). When I implemented content-indexed deltas, the
size of the SQLite database for a full clone of mozilla-unified
dropped:

before: 2,554,261,504 bytes
after:  2,488,754,176 bytes

Surprisingly, this is still larger than the bytes size of revlog
files:

revlog files: 2,104,861,230 bytes
du -b:        2,254,381,614

I would have expected storage to be smaller since we're not limiting
delta chain length and since we're using zstd instead of zlib. I
suspect the SQLite indexes and per-column overhead account for the
bulk of the differences. (Keep in mind that revlog uses a 64-byte
packed struct for revision index data and deltas are stored without
padding. Aside from the 12 unused bytes in the 32 byte node field,
revlogs are pretty efficient.) Another source of overhead is file
name storage. With revlogs, file names are stored in the filesystem.
But with SQLite, we need to store file names in the database. This is
roughly equivalent to the size of the fncache file, which for the
mozilla-unified repository is ~34MB.

Since the SQLite database isn't append-only and since delta chains
can reference any delta, this opens some interesting possibilities.
For example, we could store deltas in reverse, such that fulltexts
are stored for newer revisions and deltas are applied to reconstruct
older revisions. This is likely a more optimal storage strategy for
version control, as new data tends to be more frequently accessed
than old data. We would obviously need wire protocol support for
transferring revision data from newest to oldest. And we would
probably need some kind of mechanism for "re-encoding" stores. But
it should be doable.

This extension is very much experimental quality. There are a handful
of features that don't work. It probably isn't suitable for day-to-day
use. But it could be used in limited cases (e.g. read-only checkouts
like in CI). And it is also a good proving ground for alternate
storage backends. As we continue to define interfaces for all things
storage, it will be useful to have a viable alternate storage backend
to see how things shake out in practice.

test-storage.py passes on Python 2 and introduces no new test failures on
Python 3. Having the storage-level unit tests has proved to be insanely
useful when developing this extension. Those tests caught numerous bugs
during development and I'm convinced this style of testing is the way
forward for ensuring alternate storage backends work as intended. Of
course, test coverage isn't close to what it needs to be. But it is
a start. And what coverage we have gives me confidence that basic store
functionality is implemented properly.

Differential Revision: https://phab.mercurial-scm.org/D4928

This test is a duplicate of 'test-http.t' feel free to factor out
parts that are not bundle1/bundle2 specific.

#testcases sshv1 sshv2

#if sshv2
  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > sshpeer.advertise-v2 = true
  > sshserver.support-v2 = true
  > EOF
#endif

  $ cat << EOF >> $HGRCPATH
  > [devel]
  > # This test is dedicated to interaction through old bundle
  > legacy.exchange = bundle1
  > EOF


This test tries to exercise the ssh functionality with a dummy script

creating 'remote' repo

  $ hg init remote
  $ cd remote
  $ echo this > foo
  $ echo this > fooO
  $ hg ci -A -m "init" foo fooO

insert a closed branch (issue4428)

  $ hg up null
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ hg branch closed
  marked working directory as branch closed
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -mc0
  $ hg ci --close-branch -mc1
  $ hg up -q default

configure for serving

  $ cat <<EOF > .hg/hgrc
  > [server]
  > uncompressed = True
  > 
  > [hooks]
  > changegroup = sh -c "printenv.py changegroup-in-remote 0 ../dummylog"
  > EOF
  $ cd $TESTTMP

repo not found error

  $ hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/nonexistent local
  remote: abort: repository nonexistent not found!
  abort: no suitable response from remote hg!
  [255]

non-existent absolute path

#if no-msys
  $ hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy//`pwd`/nonexistent local
  remote: abort: repository /$TESTTMP/nonexistent not found!
  abort: no suitable response from remote hg!
  [255]
#endif

clone remote via stream

#if no-reposimplestore

  $ hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" --stream ssh://user@dummy/remote local-stream
  streaming all changes
  4 files to transfer, 602 bytes of data
  transferred 602 bytes in * seconds (*) (glob)
  searching for changes
  no changes found
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd local-stream
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 3 changesets with 2 changes to 2 files
  $ hg branches
  default                        0:1160648e36ce
  $ cd $TESTTMP

clone bookmarks via stream

  $ hg -R local-stream book mybook
  $ hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" --stream ssh://user@dummy/local-stream stream2
  streaming all changes
  4 files to transfer, 602 bytes of data
  transferred 602 bytes in * seconds (*) (glob)
  searching for changes
  no changes found
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd stream2
  $ hg book
     mybook                    0:1160648e36ce
  $ cd $TESTTMP
  $ rm -rf local-stream stream2

#endif

clone remote via pull

  $ hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/remote local
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 2 files
  new changesets 1160648e36ce:ad076bfb429d
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

verify

  $ cd local
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 3 changesets with 2 changes to 2 files
  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > changegroup = sh -c "printenv.py changegroup-in-local 0 ../dummylog"
  > EOF

empty default pull

  $ hg paths
  default = ssh://user@dummy/remote
  $ hg pull -e "\"$PYTHON\" \"$TESTDIR/dummyssh\""
  pulling from ssh://user@dummy/remote
  searching for changes
  no changes found

pull from wrong ssh URL

  $ hg pull -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/doesnotexist
  pulling from ssh://user@dummy/doesnotexist
  remote: abort: repository doesnotexist not found!
  abort: no suitable response from remote hg!
  [255]

local change

  $ echo bleah > foo
  $ hg ci -m "add"

updating rc

  $ echo "default-push = ssh://user@dummy/remote" >> .hg/hgrc
  $ echo "[ui]" >> .hg/hgrc
  $ echo "ssh = \"$PYTHON\" \"$TESTDIR/dummyssh\"" >> .hg/hgrc

find outgoing

  $ hg out ssh://user@dummy/remote
  comparing with ssh://user@dummy/remote
  searching for changes
  changeset:   3:a28a9d1a809c
  tag:         tip
  parent:      0:1160648e36ce
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add
  

find incoming on the remote side

  $ hg incoming -R ../remote -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/local
  comparing with ssh://user@dummy/local
  searching for changes
  changeset:   3:a28a9d1a809c
  tag:         tip
  parent:      0:1160648e36ce
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add
  

find incoming on the remote side (using absolute path)

  $ hg incoming -R ../remote -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" "ssh://user@dummy/`pwd`"
  comparing with ssh://user@dummy/$TESTTMP/local
  searching for changes
  changeset:   3:a28a9d1a809c
  tag:         tip
  parent:      0:1160648e36ce
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add
  

push

  $ hg push
  pushing to ssh://user@dummy/remote
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  $ cd $TESTTMP/remote

check remote tip

  $ hg tip
  changeset:   3:a28a9d1a809c
  tag:         tip
  parent:      0:1160648e36ce
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add
  
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 4 changesets with 3 changes to 2 files
  $ hg cat -r tip foo
  bleah
  $ echo z > z
  $ hg ci -A -m z z
  created new head

test pushkeys and bookmarks

  $ cd $TESTTMP/local
  $ hg debugpushkey --config ui.ssh="\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/remote namespaces
  bookmarks	
  namespaces	
  phases	
  $ hg book foo -r 0
  $ hg out -B
  comparing with ssh://user@dummy/remote
  searching for changed bookmarks
     foo                       1160648e36ce
  $ hg push -B foo
  pushing to ssh://user@dummy/remote
  searching for changes
  no changes found
  exporting bookmark foo
  [1]
  $ hg debugpushkey --config ui.ssh="\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/remote bookmarks
  foo	1160648e36cec0054048a7edc4110c6f84fde594
  $ hg book -f foo
  $ hg push --traceback
  pushing to ssh://user@dummy/remote
  searching for changes
  no changes found
  updating bookmark foo
  [1]
  $ hg book -d foo
  $ hg in -B
  comparing with ssh://user@dummy/remote
  searching for changed bookmarks
     foo                       a28a9d1a809c
  $ hg book -f -r 0 foo
  $ hg pull -B foo
  pulling from ssh://user@dummy/remote
  no changes found
  updating bookmark foo
  $ hg book -d foo
  $ hg push -B foo
  pushing to ssh://user@dummy/remote
  searching for changes
  no changes found
  deleting remote bookmark foo
  [1]

a bad, evil hook that prints to stdout

  $ cat <<EOF > $TESTTMP/badhook
  > import sys
  > sys.stdout.write("KABOOM\n")
  > EOF

  $ echo '[hooks]' >> ../remote/.hg/hgrc
  $ echo "changegroup.stdout = \"$PYTHON\" $TESTTMP/badhook" >> ../remote/.hg/hgrc
  $ echo r > r
  $ hg ci -A -m z r

push should succeed even though it has an unexpected response

  $ hg push
  pushing to ssh://user@dummy/remote
  searching for changes
  remote has heads on branch 'default' that are not known locally: 6c0482d977a3
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: KABOOM
  $ hg -R ../remote heads
  changeset:   5:1383141674ec
  tag:         tip
  parent:      3:a28a9d1a809c
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     z
  
  changeset:   4:6c0482d977a3
  parent:      0:1160648e36ce
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     z
  

clone bookmarks

  $ hg -R ../remote bookmark test
  $ hg -R ../remote bookmarks
   * test                      4:6c0482d977a3
  $ hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/remote local-bookmarks
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 6 changesets with 5 changes to 4 files (+1 heads)
  new changesets 1160648e36ce:1383141674ec
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R local-bookmarks bookmarks
     test                      4:6c0482d977a3

passwords in ssh urls are not supported
(we use a glob here because different Python versions give different
results here)

  $ hg push ssh://user:erroneouspwd@dummy/remote
  pushing to ssh://user:*@dummy/remote (glob)
  abort: password in URL not supported!
  [255]

  $ cd $TESTTMP

hide outer repo
  $ hg init

Test remote paths with spaces (issue2983):

  $ hg init --ssh "\"$PYTHON\" \"$TESTDIR/dummyssh\"" "ssh://user@dummy/a repo"
  $ touch "$TESTTMP/a repo/test"
  $ hg -R 'a repo' commit -A -m "test"
  adding test
  $ hg -R 'a repo' tag tag
  $ hg id --ssh "\"$PYTHON\" \"$TESTDIR/dummyssh\"" "ssh://user@dummy/a repo"
  73649e48688a

  $ hg id --ssh "\"$PYTHON\" \"$TESTDIR/dummyssh\"" "ssh://user@dummy/a repo#noNoNO"
  abort: unknown revision 'noNoNO'!
  [255]

Test (non-)escaping of remote paths with spaces when cloning (issue3145):

  $ hg clone --ssh "\"$PYTHON\" \"$TESTDIR/dummyssh\"" "ssh://user@dummy/a repo"
  destination directory: a repo
  abort: destination 'a repo' is not empty
  [255]

Test hg-ssh using a helper script that will restore PYTHONPATH (which might
have been cleared by a hg.exe wrapper) and invoke hg-ssh with the right
parameters:

  $ cat > ssh.sh << EOF
  > userhost="\$1"
  > SSH_ORIGINAL_COMMAND="\$2"
  > export SSH_ORIGINAL_COMMAND
  > PYTHONPATH="$PYTHONPATH"
  > export PYTHONPATH
  > "$PYTHON" "$TESTDIR/../contrib/hg-ssh" "$TESTTMP/a repo"
  > EOF

  $ hg id --ssh "sh ssh.sh" "ssh://user@dummy/a repo"
  73649e48688a

  $ hg id --ssh "sh ssh.sh" "ssh://user@dummy/a'repo"
  remote: Illegal repository "$TESTTMP/a'repo"
  abort: no suitable response from remote hg!
  [255]

  $ hg id --ssh "sh ssh.sh" --remotecmd hacking "ssh://user@dummy/a'repo"
  remote: Illegal command "hacking -R 'a'\''repo' serve --stdio"
  abort: no suitable response from remote hg!
  [255]

  $ SSH_ORIGINAL_COMMAND="'hg' serve -R 'a'repo' --stdio" "$PYTHON" "$TESTDIR/../contrib/hg-ssh"
  Illegal command "'hg' serve -R 'a'repo' --stdio": No closing quotation
  [255]

Test hg-ssh in read-only mode:

  $ cat > ssh.sh << EOF
  > userhost="\$1"
  > SSH_ORIGINAL_COMMAND="\$2"
  > export SSH_ORIGINAL_COMMAND
  > PYTHONPATH="$PYTHONPATH"
  > export PYTHONPATH
  > "$PYTHON" "$TESTDIR/../contrib/hg-ssh" --read-only "$TESTTMP/remote"
  > EOF

  $ hg clone --ssh "sh ssh.sh" "ssh://user@dummy/$TESTTMP/remote" read-only-local
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 6 changesets with 5 changes to 4 files (+1 heads)
  new changesets 1160648e36ce:1383141674ec
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd read-only-local
  $ echo "baz" > bar
  $ hg ci -A -m "unpushable commit" bar
  $ hg push --ssh "sh ../ssh.sh"
  pushing to ssh://user@dummy/*/remote (glob)
  searching for changes
  remote: Permission denied
  remote: abort: pretxnopen.hg-ssh hook failed
  remote: Permission denied
  remote: pushkey-abort: prepushkey.hg-ssh hook failed
  updating 6c0482d977a3 to public failed!
  [1]

  $ cd $TESTTMP

stderr from remote commands should be printed before stdout from local code (issue4336)

  $ hg clone remote stderr-ordering
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd stderr-ordering
  $ cat >> localwrite.py << EOF
  > from mercurial import exchange, extensions
  > 
  > def wrappedpush(orig, repo, *args, **kwargs):
  >     res = orig(repo, *args, **kwargs)
  >     repo.ui.write(b'local stdout\n')
  >     return res
  > 
  > def extsetup(ui):
  >     extensions.wrapfunction(exchange, b'push', wrappedpush)
  > EOF

  $ cat >> .hg/hgrc << EOF
  > [paths]
  > default-push = ssh://user@dummy/remote
  > [ui]
  > ssh = "$PYTHON" "$TESTDIR/dummyssh"
  > [extensions]
  > localwrite = localwrite.py
  > EOF

  $ echo localwrite > foo
  $ hg commit -m 'testing localwrite'
  $ hg push
  pushing to ssh://user@dummy/remote
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: KABOOM
  local stdout

debug output

  $ hg pull --debug ssh://user@dummy/remote
  pulling from ssh://user@dummy/remote
  running .* ".*/dummyssh" ['"]user@dummy['"] ('|")hg -R remote serve --stdio('|") (re)
  sending upgrade request: * proto=exp-ssh-v2-0003 (glob) (sshv2 !)
  sending hello command
  sending between command
  remote: 427 (sshv1 !)
  protocol upgraded to exp-ssh-v2-0003 (sshv2 !)
  remote: capabilities: batch branchmap $USUAL_BUNDLE2_CAPS$ changegroupsubset getbundle known lookup protocaps pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash
  remote: 1 (sshv1 !)
  sending protocaps command
  preparing listkeys for "bookmarks"
  sending listkeys command
  received listkey for "bookmarks": 45 bytes
  query 1; heads
  sending batch command
  searching for changes
  all remote heads known locally
  no changes found
  preparing listkeys for "phases"
  sending listkeys command
  received listkey for "phases": 15 bytes
  checking for updated bookmarks

  $ cd $TESTTMP

  $ cat dummylog
  Got arguments 1:user@dummy 2:hg -R nonexistent serve --stdio
  Got arguments 1:user@dummy 2:hg -R /$TESTTMP/nonexistent serve --stdio (no-msys !)
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  Got arguments 1:user@dummy 2:hg -R local-stream serve --stdio (no-reposimplestore !)
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio (no-reposimplestore !)
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio (no-reposimplestore !)
  Got arguments 1:user@dummy 2:hg -R doesnotexist serve --stdio
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  Got arguments 1:user@dummy 2:hg -R local serve --stdio
  Got arguments 1:user@dummy 2:hg -R $TESTTMP/local serve --stdio
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  changegroup-in-remote hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=a28a9d1a809cab7d4e2fde4bee738a9ede948b60 HG_NODE_LAST=a28a9d1a809cab7d4e2fde4bee738a9ede948b60 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:ssh:$LOCALIP
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  changegroup-in-remote hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=1383141674ec756a6056f6a9097618482fe0f4a6 HG_NODE_LAST=1383141674ec756a6056f6a9097618482fe0f4a6 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:ssh:$LOCALIP
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  Got arguments 1:user@dummy 2:hg init 'a repo'
  Got arguments 1:user@dummy 2:hg -R 'a repo' serve --stdio
  Got arguments 1:user@dummy 2:hg -R 'a repo' serve --stdio
  Got arguments 1:user@dummy 2:hg -R 'a repo' serve --stdio
  Got arguments 1:user@dummy 2:hg -R 'a repo' serve --stdio
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio
  changegroup-in-remote hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=65c38f4125f9602c8db4af56530cc221d93b8ef8 HG_NODE_LAST=65c38f4125f9602c8db4af56530cc221d93b8ef8 HG_SOURCE=serve HG_TXNID=TXN:$ID$ HG_URL=remote:ssh:$LOCALIP
  Got arguments 1:user@dummy 2:hg -R remote serve --stdio

remote hook failure is attributed to remote

  $ cat > $TESTTMP/failhook << EOF
  > def hook(ui, repo, **kwargs):
  >     ui.write(b'hook failure!\n')
  >     ui.flush()
  >     return 1
  > EOF

  $ echo "pretxnchangegroup.fail = python:$TESTTMP/failhook:hook" >> remote/.hg/hgrc

  $ hg -q --config ui.ssh="\"$PYTHON\" $TESTDIR/dummyssh" clone ssh://user@dummy/remote hookout
  $ cd hookout
  $ touch hookfailure
  $ hg -q commit -A -m 'remote hook failure'
  $ hg --config ui.ssh="\"$PYTHON\" $TESTDIR/dummyssh" push
  pushing to ssh://user@dummy/remote
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: hook failure!
  remote: transaction abort!
  remote: rollback completed
  remote: abort: pretxnchangegroup.fail hook failed
  [1]

abort during pull is properly reported as such

  $ echo morefoo >> ../remote/foo
  $ hg -R ../remote commit --message "more foo to be pulled"
  $ cat >> ../remote/.hg/hgrc << EOF
  > [extensions]
  > crash = ${TESTDIR}/crashgetbundler.py
  > EOF
  $ hg --config ui.ssh="\"$PYTHON\" $TESTDIR/dummyssh" pull
  pulling from ssh://user@dummy/remote
  searching for changes
  adding changesets
  remote: abort: this is an exercise
  transaction abort!
  rollback completed
  abort: stream ended unexpectedly (got 0 bytes, expected 4)
  [255]