view tests/test-bisect.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

  $ hg init


committing changes

  $ count=0
  $ echo > a
  $ while test $count -lt 32 ; do
  >     echo 'a' >> a
  >     test $count -eq 0 && hg add
  >     hg ci -m "msg $count" -d "$count 0"
  >     count=`expr $count + 1`
  > done
  adding a


  $ hg log
  changeset:   31:58c80a7c8a40
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:31 1970 +0000
  summary:     msg 31
  
  changeset:   30:ed2d2f24b11c
  user:        test
  date:        Thu Jan 01 00:00:30 1970 +0000
  summary:     msg 30
  
  changeset:   29:b5bd63375ab9
  user:        test
  date:        Thu Jan 01 00:00:29 1970 +0000
  summary:     msg 29
  
  changeset:   28:8e0c2264c8af
  user:        test
  date:        Thu Jan 01 00:00:28 1970 +0000
  summary:     msg 28
  
  changeset:   27:288867a866e9
  user:        test
  date:        Thu Jan 01 00:00:27 1970 +0000
  summary:     msg 27
  
  changeset:   26:3efc6fd51aeb
  user:        test
  date:        Thu Jan 01 00:00:26 1970 +0000
  summary:     msg 26
  
  changeset:   25:02a84173a97a
  user:        test
  date:        Thu Jan 01 00:00:25 1970 +0000
  summary:     msg 25
  
  changeset:   24:10e0acd3809e
  user:        test
  date:        Thu Jan 01 00:00:24 1970 +0000
  summary:     msg 24
  
  changeset:   23:5ec79163bff4
  user:        test
  date:        Thu Jan 01 00:00:23 1970 +0000
  summary:     msg 23
  
  changeset:   22:06c7993750ce
  user:        test
  date:        Thu Jan 01 00:00:22 1970 +0000
  summary:     msg 22
  
  changeset:   21:e5db6aa3fe2a
  user:        test
  date:        Thu Jan 01 00:00:21 1970 +0000
  summary:     msg 21
  
  changeset:   20:7128fb4fdbc9
  user:        test
  date:        Thu Jan 01 00:00:20 1970 +0000
  summary:     msg 20
  
  changeset:   19:52798545b482
  user:        test
  date:        Thu Jan 01 00:00:19 1970 +0000
  summary:     msg 19
  
  changeset:   18:86977a90077e
  user:        test
  date:        Thu Jan 01 00:00:18 1970 +0000
  summary:     msg 18
  
  changeset:   17:03515f4a9080
  user:        test
  date:        Thu Jan 01 00:00:17 1970 +0000
  summary:     msg 17
  
  changeset:   16:a2e6ea4973e9
  user:        test
  date:        Thu Jan 01 00:00:16 1970 +0000
  summary:     msg 16
  
  changeset:   15:e7fa0811edb0
  user:        test
  date:        Thu Jan 01 00:00:15 1970 +0000
  summary:     msg 15
  
  changeset:   14:ce8f0998e922
  user:        test
  date:        Thu Jan 01 00:00:14 1970 +0000
  summary:     msg 14
  
  changeset:   13:9d7d07bc967c
  user:        test
  date:        Thu Jan 01 00:00:13 1970 +0000
  summary:     msg 13
  
  changeset:   12:1941b52820a5
  user:        test
  date:        Thu Jan 01 00:00:12 1970 +0000
  summary:     msg 12
  
  changeset:   11:7b4cd9578619
  user:        test
  date:        Thu Jan 01 00:00:11 1970 +0000
  summary:     msg 11
  
  changeset:   10:7c5eff49a6b6
  user:        test
  date:        Thu Jan 01 00:00:10 1970 +0000
  summary:     msg 10
  
  changeset:   9:eb44510ef29a
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     msg 9
  
  changeset:   8:453eb4dba229
  user:        test
  date:        Thu Jan 01 00:00:08 1970 +0000
  summary:     msg 8
  
  changeset:   7:03750880c6b5
  user:        test
  date:        Thu Jan 01 00:00:07 1970 +0000
  summary:     msg 7
  
  changeset:   6:a3d5c6fdf0d3
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     msg 6
  
  changeset:   5:7874a09ea728
  user:        test
  date:        Thu Jan 01 00:00:05 1970 +0000
  summary:     msg 5
  
  changeset:   4:9b2ba8336a65
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     msg 4
  
  changeset:   3:b53bea5e2fcb
  user:        test
  date:        Thu Jan 01 00:00:03 1970 +0000
  summary:     msg 3
  
  changeset:   2:db07c04beaca
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     msg 2
  
  changeset:   1:5cd978ea5149
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     msg 1
  
  changeset:   0:b99c7b9c8e11
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     msg 0
  

  $ hg up -C
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

bisect test

  $ hg bisect -r
  $ hg bisect -b
  $ hg status -v
  # The repository is in an unfinished *bisect* state.
  
  # To mark the changeset good:    hg bisect --good
  # To mark the changeset bad:     hg bisect --bad
  # To abort:                      hg bisect --reset
  
  $ hg status -v --config commands.status.skipstates=bisect
  $ hg summary
  parent: 31:58c80a7c8a40 tip
   msg 31
  branch: default
  commit: (clean)
  update: (current)
  phases: 32 draft
  $ hg bisect -g 1
  Testing changeset 16:a2e6ea4973e9 (30 changesets remaining, ~4 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -g
  Testing changeset 23:5ec79163bff4 (15 changesets remaining, ~3 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

skip

  $ hg bisect -s
  Testing changeset 24:10e0acd3809e (15 changesets remaining, ~3 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -g
  Testing changeset 27:288867a866e9 (7 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -g
  Testing changeset 29:b5bd63375ab9 (4 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -b
  Testing changeset 28:8e0c2264c8af (2 changesets remaining, ~1 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -g
  The first bad revision is:
  changeset:   29:b5bd63375ab9
  user:        test
  date:        Thu Jan 01 00:00:29 1970 +0000
  summary:     msg 29
  

mark revsets instead of single revs

  $ hg bisect -r
  $ hg bisect -b "0::3"
  $ hg bisect -s "13::16"
  $ hg bisect -g "26::tip"
  Testing changeset 12:1941b52820a5 (23 changesets remaining, ~4 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat .hg/bisect.state
  bad b99c7b9c8e11558adef3fad9af211c58d46f325b
  bad 5cd978ea51499179507ee7b6f340d2dbaa401185
  bad db07c04beaca44cf24832541e7f4a2346a95275b
  bad b53bea5e2fcb30d3e00bd3409507a5659ce0fd8b
  current 1941b52820a544549596820a8ae006842b0e2c64
  good 3efc6fd51aeb8594398044c6c846ca59ae021203
  good 288867a866e9adb7a29880b66936c874b80f4651
  good 8e0c2264c8af790daf3585ada0669d93dee09c83
  good b5bd63375ab9a290419f2024b7f4ee9ea7ce90a8
  good ed2d2f24b11c368fa8aa0da9f4e1db580abade59
  good 58c80a7c8a4025a94cedaf7b4a4e3124e8909a96
  skip 9d7d07bc967ca98ad0600c24953fd289ad5fa991
  skip ce8f0998e922c179e80819d5066fbe46e2998784
  skip e7fa0811edb063f6319531f0d0a865882138e180
  skip a2e6ea4973e9196ddd3386493b0c214b41fd97d3

bisect reverse test

  $ hg bisect -r
  $ hg bisect -b null
  $ hg bisect -g tip
  Testing changeset 15:e7fa0811edb0 (32 changesets remaining, ~5 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -g
  Testing changeset 7:03750880c6b5 (16 changesets remaining, ~4 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

skip

  $ hg bisect -s
  Testing changeset 6:a3d5c6fdf0d3 (16 changesets remaining, ~4 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -g
  Testing changeset 2:db07c04beaca (7 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -g
  Testing changeset 0:b99c7b9c8e11 (3 changesets remaining, ~1 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -b
  Testing changeset 1:5cd978ea5149 (2 changesets remaining, ~1 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -g
  The first good revision is:
  changeset:   1:5cd978ea5149
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     msg 1
  

  $ hg bisect -r
  $ hg bisect -g tip
  $ hg bisect -b tip
  abort: inconsistent state, 31:58c80a7c8a40 is good and bad
  [255]

  $ hg bisect -r
  $ hg bisect -g null
  $ hg bisect -bU tip
  Testing changeset 15:e7fa0811edb0 (32 changesets remaining, ~5 tests)
  $ hg id
  5cd978ea5149


Issue1228: hg bisect crashes when you skip the last rev in bisection
Issue1182: hg bisect exception

  $ hg bisect -r
  $ hg bisect -b 4
  $ hg bisect -g 0
  Testing changeset 2:db07c04beaca (4 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -s
  Testing changeset 1:5cd978ea5149 (4 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -s
  Testing changeset 3:b53bea5e2fcb (4 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -s
  Due to skipped revisions, the first bad revision could be any of:
  changeset:   1:5cd978ea5149
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     msg 1
  
  changeset:   2:db07c04beaca
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     msg 2
  
  changeset:   3:b53bea5e2fcb
  user:        test
  date:        Thu Jan 01 00:00:03 1970 +0000
  summary:     msg 3
  
  changeset:   4:9b2ba8336a65
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     msg 4
  


reproduce non converging bisect, issue1182

  $ hg bisect -r
  $ hg bisect -g 0
  $ hg bisect -b 2
  Testing changeset 1:5cd978ea5149 (2 changesets remaining, ~1 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -s
  Due to skipped revisions, the first bad revision could be any of:
  changeset:   1:5cd978ea5149
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     msg 1
  
  changeset:   2:db07c04beaca
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     msg 2
  


test no action

  $ hg bisect -r
  $ hg bisect
  abort: cannot bisect (no known good revisions)
  [255]


reproduce AssertionError, issue1445

  $ hg bisect -r
  $ hg bisect -b 6
  $ hg bisect -g 0
  Testing changeset 3:b53bea5e2fcb (6 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -s
  Testing changeset 2:db07c04beaca (6 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -s
  Testing changeset 4:9b2ba8336a65 (6 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -s
  Testing changeset 1:5cd978ea5149 (6 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -s
  Testing changeset 5:7874a09ea728 (6 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect -g
  The first bad revision is:
  changeset:   6:a3d5c6fdf0d3
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     msg 6
  
  $ hg log -r "bisect(good)"
  changeset:   0:b99c7b9c8e11
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     msg 0
  
  changeset:   5:7874a09ea728
  user:        test
  date:        Thu Jan 01 00:00:05 1970 +0000
  summary:     msg 5
  
  $ hg log -r "bisect(bad)"
  changeset:   6:a3d5c6fdf0d3
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     msg 6
  
  $ hg log -r "bisect(current)"
  changeset:   5:7874a09ea728
  user:        test
  date:        Thu Jan 01 00:00:05 1970 +0000
  summary:     msg 5
  
  $ hg log -r "bisect(skip)"
  changeset:   1:5cd978ea5149
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     msg 1
  
  changeset:   2:db07c04beaca
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     msg 2
  
  changeset:   3:b53bea5e2fcb
  user:        test
  date:        Thu Jan 01 00:00:03 1970 +0000
  summary:     msg 3
  
  changeset:   4:9b2ba8336a65
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     msg 4
  

test legacy bisected() keyword

  $ hg log -r "bisected(bad)"
  changeset:   6:a3d5c6fdf0d3
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     msg 6
  

  $ set +e

test invalid command
assuming that the shell returns 127 if command not found ...

  $ hg bisect -r
  $ hg bisect --command 'exit 127'
  abort: failed to execute exit 127
  [255]


test bisecting command

  $ cat > script.py <<EOF
  > #!$PYTHON
  > from __future__ import absolute_import
  > import sys
  > from mercurial import hg, ui as uimod
  > repo = hg.repository(uimod.ui.load(), b'.')
  > if repo[b'.'].rev() < 6:
  >     sys.exit(1)
  > EOF
  $ chmod +x script.py
  $ hg bisect -r
  $ hg up -qr tip
  $ hg bisect --command "\"$PYTHON\" \"$TESTTMP/script.py\" and some parameters"
  changeset 31:58c80a7c8a40: good
  abort: cannot bisect (no known bad revisions)
  [255]
  $ hg up -qr 0
  $ hg bisect --command "\"$PYTHON\" \"$TESTTMP/script.py\" and some parameters"
  changeset 0:b99c7b9c8e11: bad
  changeset 15:e7fa0811edb0: good
  changeset 7:03750880c6b5: good
  changeset 3:b53bea5e2fcb: bad
  changeset 5:7874a09ea728: bad
  changeset 6:a3d5c6fdf0d3: good
  The first good revision is:
  changeset:   6:a3d5c6fdf0d3
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     msg 6
  


test bisecting via a command without updating the working dir, and
ensure that the bisect state file is updated before running a test
command

  $ hg update null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ cat > script.sh <<'EOF'
  > #!/bin/sh
  > test -n "$HG_NODE" || (echo HG_NODE missing; exit 127)
  > current="`hg log -r \"bisect(current)\" --template {node}`"
  > test "$current" = "$HG_NODE" || (echo current is bad: $current; exit 127)
  > rev="`hg log -r $HG_NODE --template {rev}`"
  > test "$rev" -ge 6
  > EOF
  $ chmod +x script.sh
  $ hg bisect -r
  $ hg bisect --good tip --noupdate
  $ hg bisect --bad 0 --noupdate
  Testing changeset 15:e7fa0811edb0 (31 changesets remaining, ~4 tests)
  $ hg bisect --command "sh \"$TESTTMP/script.sh\" and some params" --noupdate
  changeset 15:e7fa0811edb0: good
  changeset 7:03750880c6b5: good
  changeset 3:b53bea5e2fcb: bad
  changeset 5:7874a09ea728: bad
  changeset 6:a3d5c6fdf0d3: good
  The first good revision is:
  changeset:   6:a3d5c6fdf0d3
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     msg 6
  

ensure that we still don't have a working dir

  $ hg parents


test the same case, this time with updating

  $ cat > script.sh <<'EOF'
  > #!/bin/sh
  > test -n "$HG_NODE" || (echo HG_NODE missing; exit 127)
  > current="`hg log -r \"bisect(current)\" --template {node}`"
  > test "$current" = "$HG_NODE" || (echo current is bad: $current; exit 127)
  > rev="`hg log -r . --template {rev}`"
  > test "$rev" -ge 6
  > EOF
  $ chmod +x script.sh
  $ hg bisect -r
  $ hg up -qr tip
  $ hg bisect --command "sh \"$TESTTMP/script.sh\" and some params"
  changeset 31:58c80a7c8a40: good
  abort: cannot bisect (no known bad revisions)
  [255]
  $ hg up -qr 0
  $ hg bisect --command "sh \"$TESTTMP/script.sh\" and some params"
  changeset 0:b99c7b9c8e11: bad
  changeset 15:e7fa0811edb0: good
  changeset 7:03750880c6b5: good
  changeset 3:b53bea5e2fcb: bad
  changeset 5:7874a09ea728: bad
  changeset 6:a3d5c6fdf0d3: good
  The first good revision is:
  changeset:   6:a3d5c6fdf0d3
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     msg 6
  
  $ hg graft -q 15
  warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
  abort: unresolved conflicts, can't continue
  (use 'hg resolve' and 'hg graft --continue')
  [255]
  $ hg bisect --reset
  $ hg up -C .
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Check that bisect does not break on obsolete changesets
=========================================================

  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > evolution.createmarkers=True
  > EOF

tip is obsolete
---------------------

  $ hg debugobsolete `hg id --debug -i -r tip`
  obsoleted 1 changesets
  $ hg bisect --reset
  $ hg bisect --good 15
  $ hg bisect --bad 30
  Testing changeset 22:06c7993750ce (15 changesets remaining, ~3 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect --command true
  changeset 22:06c7993750ce: good
  changeset 26:3efc6fd51aeb: good
  changeset 28:8e0c2264c8af: good
  changeset 29:b5bd63375ab9: good
  The first bad revision is:
  changeset:   30:ed2d2f24b11c
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:30 1970 +0000
  summary:     msg 30
  

Changeset in the bad:good range is obsolete
---------------------------------------------

  $ hg up 30
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo 'a' >> a
  $ hg ci -m "msg 32" -d "32 0"
  $ hg bisect --reset
  $ hg bisect --good .
  $ hg bisect --bad 25
  Testing changeset 28:8e0c2264c8af (6 changesets remaining, ~2 tests)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bisect --command true
  changeset 28:8e0c2264c8af: good
  changeset 26:3efc6fd51aeb: good
  The first good revision is:
  changeset:   26:3efc6fd51aeb
  user:        test
  date:        Thu Jan 01 00:00:26 1970 +0000
  summary:     msg 26
  
Test the validation message when exclusive options are used:

  $ hg bisect -r
  $ hg bisect -b -c false
  abort: --bad and --command are incompatible
  [255]
  $ hg bisect -b -e
  abort: --bad and --extend are incompatible
  [255]
  $ hg bisect -b -g
  abort: --bad and --good are incompatible
  [255]
  $ hg bisect -b -r
  abort: --bad and --reset are incompatible
  [255]
  $ hg bisect -b -s
  abort: --bad and --skip are incompatible
  [255]
  $ hg bisect -c false -e
  abort: --command and --extend are incompatible
  [255]
  $ hg bisect -c false -g
  abort: --command and --good are incompatible
  [255]
  $ hg bisect -c false -r
  abort: --command and --reset are incompatible
  [255]
  $ hg bisect -c false -s
  abort: --command and --skip are incompatible
  [255]
  $ hg bisect -e -g
  abort: --extend and --good are incompatible
  [255]
  $ hg bisect -e -r
  abort: --extend and --reset are incompatible
  [255]
  $ hg bisect -e -s
  abort: --extend and --skip are incompatible
  [255]
  $ hg bisect -g -r
  abort: --good and --reset are incompatible
  [255]
  $ hg bisect -g -s
  abort: --good and --skip are incompatible
  [255]
  $ hg bisect -r -s
  abort: --reset and --skip are incompatible
  [255]