view tests/test-rebase-collapse.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

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > mq=
  > drawdag=$TESTDIR/drawdag.py
  > 
  > [phases]
  > publish=False
  > 
  > [alias]
  > tglog = log -G --template "{rev}: {node|short} '{desc}' {branches}\n"
  > tglogp = log -G --template "{rev}: {node|short} {phase} '{desc}' {branches}\n"
  > EOF

Highest phase of source commits is used:

  $ hg init phase
  $ cd phase
  $ hg debugdrawdag << 'EOF'
  >   D
  >   |
  > F C
  > | |
  > E B
  > |/
  > A
  > EOF

  $ hg phase --force --secret D

  $ cat > $TESTTMP/editor.sh <<EOF
  > echo "==== before editing"
  > cat \$1
  > echo "===="
  > echo "edited manually" >> \$1
  > EOF
  $ HGEDITOR="sh $TESTTMP/editor.sh" hg rebase --collapse --keepbranches -e --dest F
  rebasing 1:112478962961 "B" (B)
  rebasing 3:26805aba1e60 "C" (C)
  rebasing 5:f585351a92f8 "D" (D tip)
  ==== before editing
  Collapsed revision
  * B
  * C
  * D
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to abort commit.
  HG: --
  HG: user: test
  HG: branch 'default'
  HG: added B
  HG: added C
  HG: added D
  ====
  saved backup bundle to $TESTTMP/phase/.hg/strip-backup/112478962961-cb2a9b47-rebase.hg

  $ hg tglogp
  o  3: 92fa5f5fe108 secret 'Collapsed revision
  |  * B
  |  * C
  |  * D
  |
  |
  |  edited manually'
  o  2: 64a8289d2492 draft 'F'
  |
  o  1: 7fb047a69f22 draft 'E'
  |
  o  0: 426bada5c675 draft 'A'
  
  $ hg manifest --rev tip
  A
  B
  C
  D
  E
  F

  $ cd ..


Merge gets linearized:

  $ hg init linearized-merge
  $ cd linearized-merge

  $ hg debugdrawdag << 'EOF'
  > F D
  > |/|
  > C B
  > |/
  > A
  > EOF

  $ hg phase --force --secret D
  $ hg rebase --source B --collapse --dest F
  rebasing 1:112478962961 "B" (B)
  rebasing 3:4e4f9194f9f1 "D" (D)
  saved backup bundle to $TESTTMP/linearized-merge/.hg/strip-backup/112478962961-e389075b-rebase.hg

  $ hg tglog
  o  3: 5bdc08b7da2b 'Collapsed revision
  |  * B
  |  * D'
  o  2: afc707c82df0 'F'
  |
  o  1: dc0947a82db8 'C'
  |
  o  0: 426bada5c675 'A'
  
  $ hg manifest --rev tip
  A
  B
  C
  F

  $ cd ..

Custom message:

  $ hg init message
  $ cd message

  $ hg debugdrawdag << 'EOF'
  >   C
  >   |
  > D B
  > |/
  > A
  > EOF


  $ hg rebase --base B -m 'custom message'
  abort: message can only be specified with collapse
  [255]

  $ cat > $TESTTMP/checkeditform.sh <<EOF
  > env | grep HGEDITFORM
  > true
  > EOF
  $ HGEDITOR="sh $TESTTMP/checkeditform.sh" hg rebase --source B --collapse -m 'custom message' -e --dest D
  rebasing 1:112478962961 "B" (B)
  rebasing 3:26805aba1e60 "C" (C tip)
  HGEDITFORM=rebase.collapse
  saved backup bundle to $TESTTMP/message/.hg/strip-backup/112478962961-f4131707-rebase.hg

  $ hg tglog
  o  2: 2f197b9a08f3 'custom message'
  |
  o  1: b18e25de2cf5 'D'
  |
  o  0: 426bada5c675 'A'
  
  $ hg manifest --rev tip
  A
  B
  C
  D

  $ cd ..

Rebase and collapse - more than one external (fail):

  $ hg init multiple-external-parents
  $ cd multiple-external-parents

  $ hg debugdrawdag << 'EOF'
  >   G
  >   |\
  >   | F
  >   | |
  >   D E
  >   |\|
  > H C B
  >  \|/
  >   A
  > EOF

  $ hg rebase -s C --dest H --collapse
  abort: unable to collapse on top of 3, there is more than one external parent: 1, 6
  [255]

Rebase and collapse - E onto H:

  $ hg rebase -s E --dest I --collapse # root (E) is not a merge
  abort: unknown revision 'I'!
  [255]

  $ hg tglog
  o    7: 64e264db77f0 'G'
  |\
  | o  6: 11abe3fb10b8 'F'
  | |
  | o  5: 49cb92066bfd 'E'
  | |
  o |  4: 4e4f9194f9f1 'D'
  |\|
  | | o  3: 575c4b5ec114 'H'
  | | |
  o---+  2: dc0947a82db8 'C'
   / /
  o /  1: 112478962961 'B'
  |/
  o  0: 426bada5c675 'A'
  
  $ hg manifest --rev tip
  A
  B
  C
  E
  F

  $ cd ..




Test that branchheads cache is updated correctly when doing a strip in which
the parent of the ancestor node to be stripped does not become a head and also,
the parent of a node that is a child of the node stripped becomes a head (node
3). The code is now much simpler and we could just test a simpler scenario
We keep it the test this way in case new complexity is injected.

Create repo b:

  $ hg init branch-heads
  $ cd branch-heads

  $ hg debugdrawdag << 'EOF'
  >   G
  >   |\
  >   | F
  >   | |
  >   D E
  >   |\|
  > H C B
  >  \|/
  >   A
  > EOF

  $ hg heads --template="{rev}:{node} {branch}\n"
  7:64e264db77f061f16d9132b70c5a58e2461fb630 default
  3:575c4b5ec114d64b681d33f8792853568bfb2b2c default

  $ cat $TESTTMP/branch-heads/.hg/cache/branch2-served
  64e264db77f061f16d9132b70c5a58e2461fb630 7
  575c4b5ec114d64b681d33f8792853568bfb2b2c o default
  64e264db77f061f16d9132b70c5a58e2461fb630 o default

  $ hg strip 4
  saved backup bundle to $TESTTMP/branch-heads/.hg/strip-backup/4e4f9194f9f1-5ec4b5e6-backup.hg

  $ cat $TESTTMP/branch-heads/.hg/cache/branch2-served
  11abe3fb10b8689b560681094b17fe161871d043 5
  dc0947a82db884575bb76ea10ac97b08536bfa03 o default
  575c4b5ec114d64b681d33f8792853568bfb2b2c o default
  11abe3fb10b8689b560681094b17fe161871d043 o default

  $ hg heads --template="{rev}:{node} {branch}\n"
  5:11abe3fb10b8689b560681094b17fe161871d043 default
  3:575c4b5ec114d64b681d33f8792853568bfb2b2c default
  2:dc0947a82db884575bb76ea10ac97b08536bfa03 default

  $ cd ..



Preserves external parent

  $ hg init external-parent
  $ cd external-parent

  $ hg debugdrawdag << 'EOF'
  >   H
  >   |\
  >   | G
  >   | |
  >   | F # F/E = F\n
  >   | |
  >   D E # D/D = D\n
  >   |\|
  > I C B
  >  \|/
  >   A
  > EOF

  $ hg rebase -s F --dest I --collapse # root (F) is not a merge
  rebasing 6:c82b08f646f1 "F" (F)
  rebasing 7:a6db7fa104e1 "G" (G)
  rebasing 8:e1d201b72d91 "H" (H tip)
  saved backup bundle to $TESTTMP/external-parent/.hg/strip-backup/c82b08f646f1-f2721fbf-rebase.hg

  $ hg tglog
  o    6: 681daa3e686d 'Collapsed revision
  |\   * F
  | |  * G
  | |  * H'
  | | o  5: 49cb92066bfd 'E'
  | | |
  | o |  4: 09143c0bf13e 'D'
  | |\|
  o | |  3: 08ebfeb61bac 'I'
  | | |
  | o |  2: dc0947a82db8 'C'
  |/ /
  | o  1: 112478962961 'B'
  |/
  o  0: 426bada5c675 'A'
  
  $ hg manifest --rev tip
  A
  C
  D
  E
  F
  G
  I

  $ hg up tip -q
  $ cat E
  F

  $ cd ..

Rebasing from multiple bases:

  $ hg init multiple-bases
  $ cd multiple-bases
  $ hg debugdrawdag << 'EOF'
  >   C B
  > D |/
  > |/
  > A
  > EOF
  $ hg rebase --collapse -r 'B+C' -d D
  rebasing 1:fc2b737bb2e5 "B" (B)
  rebasing 2:dc0947a82db8 "C" (C)
  saved backup bundle to $TESTTMP/multiple-bases/.hg/strip-backup/dc0947a82db8-b0c1a7ea-rebase.hg
  $ hg tglog
  o  2: 2127ae44d291 'Collapsed revision
  |  * B
  |  * C'
  o  1: b18e25de2cf5 'D'
  |
  o  0: 426bada5c675 'A'
  
  $ cd ..

With non-contiguous commits:

  $ hg init non-contiguous
  $ cd non-contiguous
  $ cat >> .hg/hgrc <<EOF
  > [experimental]
  > evolution=all
  > EOF

  $ hg debugdrawdag << 'EOF'
  > F
  > |
  > E
  > |
  > D
  > |
  > C
  > |
  > B G
  > |/
  > A
  > EOF

BROKEN: should be allowed
  $ hg rebase --collapse -r 'B+D+F' -d G
  abort: unable to collapse on top of 2, there is more than one external parent: 3, 5
  [255]
  $ cd ..


  $ hg init multiple-external-parents-2
  $ cd multiple-external-parents-2
  $ hg debugdrawdag << 'EOF'
  > D       G
  > |\     /|
  > B C   E F
  >  \|   |/
  >   \ H /
  >    \|/
  >     A
  > EOF

  $ hg rebase --collapse -d H -s 'B+F'
  abort: unable to collapse on top of 5, there is more than one external parent: 1, 3
  [255]
  $ cd ..

With internal merge:

  $ hg init internal-merge
  $ cd internal-merge

  $ hg debugdrawdag << 'EOF'
  >   E
  >   |\
  >   C D
  >   |/
  > F B
  > |/
  > A
  > EOF


  $ hg rebase -s B --collapse --dest F
  rebasing 1:112478962961 "B" (B)
  rebasing 3:26805aba1e60 "C" (C)
  rebasing 4:be0ef73c17ad "D" (D)
  rebasing 5:02c4367d6973 "E" (E tip)
  saved backup bundle to $TESTTMP/internal-merge/.hg/strip-backup/112478962961-1dfb057b-rebase.hg

  $ hg tglog
  o  2: c0512a1797b0 'Collapsed revision
  |  * B
  |  * C
  |  * D
  |  * E'
  o  1: 8908a377a434 'F'
  |
  o  0: 426bada5c675 'A'
  
  $ hg manifest --rev tip
  A
  B
  C
  D
  F
  $ cd ..

Interactions between collapse and keepbranches
  $ hg init e
  $ cd e
  $ echo 'a' > a
  $ hg ci -Am 'A'
  adding a

  $ hg branch 'one'
  marked working directory as branch one
  (branches are permanent and global, did you want a bookmark?)
  $ echo 'b' > b
  $ hg ci -Am 'B'
  adding b

  $ hg branch 'two'
  marked working directory as branch two
  $ echo 'c' > c
  $ hg ci -Am 'C'
  adding c

  $ hg up -q 0
  $ echo 'd' > d
  $ hg ci -Am 'D'
  adding d

  $ hg tglog
  @  3: 41acb9dca9eb 'D'
  |
  | o  2: 8ac4a08debf1 'C' two
  | |
  | o  1: 1ba175478953 'B' one
  |/
  o  0: 1994f17a630e 'A'
  
  $ hg rebase --keepbranches --collapse -s 1 -d 3
  abort: cannot collapse multiple named branches
  [255]

  $ repeatchange() {
  >   hg checkout $1
  >   hg cp d z
  >   echo blah >> z
  >   hg commit -Am "$2" --user "$3"
  > }
  $ repeatchange 3 "E" "user1"
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ repeatchange 3 "E" "user2"
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  created new head
  $ hg tglog
  @  5: fbfb97b1089a 'E'
  |
  | o  4: f338eb3c2c7c 'E'
  |/
  o  3: 41acb9dca9eb 'D'
  |
  | o  2: 8ac4a08debf1 'C' two
  | |
  | o  1: 1ba175478953 'B' one
  |/
  o  0: 1994f17a630e 'A'
  
  $ hg rebase -s 5 -d 4
  rebasing 5:fbfb97b1089a "E" (tip)
  note: rebase of 5:fbfb97b1089a created no changes to commit
  saved backup bundle to $TESTTMP/e/.hg/strip-backup/fbfb97b1089a-553e1d85-rebase.hg
  $ hg tglog
  @  4: f338eb3c2c7c 'E'
  |
  o  3: 41acb9dca9eb 'D'
  |
  | o  2: 8ac4a08debf1 'C' two
  | |
  | o  1: 1ba175478953 'B' one
  |/
  o  0: 1994f17a630e 'A'
  
  $ hg export tip
  # HG changeset patch
  # User user1
  # Date 0 0
  #      Thu Jan 01 00:00:00 1970 +0000
  # Node ID f338eb3c2c7cc5b5915676a2376ba7ac558c5213
  # Parent  41acb9dca9eb976e84cd21fcb756b4afa5a35c09
  E
  
  diff -r 41acb9dca9eb -r f338eb3c2c7c z
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/z	Thu Jan 01 00:00:00 1970 +0000
  @@ -0,0 +1,2 @@
  +d
  +blah

  $ cd ..

Rebase, collapse and copies

  $ hg init copies
  $ cd copies
  $ hg unbundle "$TESTDIR/bundles/renames.hg"
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 11 changes to 7 files (+1 heads)
  new changesets f447d5abf5ea:338e84e2e558 (4 drafts)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg up -q tip
  $ hg tglog
  @  3: 338e84e2e558 'move2'
  |
  o  2: 6e7340ee38c0 'move1'
  |
  | o  1: 1352765a01d4 'change'
  |/
  o  0: f447d5abf5ea 'add'
  
  $ hg rebase --collapse -d 1
  rebasing 2:6e7340ee38c0 "move1"
  merging a and d to d
  merging b and e to e
  merging c and f to f
  rebasing 3:338e84e2e558 "move2" (tip)
  merging f and c to c
  merging e and g to g
  saved backup bundle to $TESTTMP/copies/.hg/strip-backup/6e7340ee38c0-ef8ef003-rebase.hg
  $ hg st
  $ hg st --copies --change tip
  A d
    a
  A g
    b
  R b
  $ hg up tip -q
  $ cat c
  c
  c
  $ cat d
  a
  a
  $ cat g
  b
  b
  $ hg log -r . --template "{file_copies}\n"
  d (a)g (b)

Test collapsing a middle revision in-place

  $ hg tglog
  @  2: 64b456429f67 'Collapsed revision
  |  * move1
  |  * move2'
  o  1: 1352765a01d4 'change'
  |
  o  0: f447d5abf5ea 'add'
  
  $ hg rebase --collapse -r 1 -d 0
  abort: can't remove original changesets with unrebased descendants
  (use --keep to keep original changesets)
  [255]

Test collapsing in place

  $ hg rebase --collapse -b . -d 0
  rebasing 1:1352765a01d4 "change"
  rebasing 2:64b456429f67 "Collapsed revision" (tip)
  saved backup bundle to $TESTTMP/copies/.hg/strip-backup/1352765a01d4-45a352ea-rebase.hg
  $ hg st --change tip --copies
  M a
  M c
  A d
    a
  A g
    b
  R b
  $ hg up tip -q
  $ cat a
  a
  a
  $ cat c
  c
  c
  $ cat d
  a
  a
  $ cat g
  b
  b
  $ cd ..


Test stripping a revision with another child

  $ hg init f
  $ cd f

  $ hg debugdrawdag << 'EOF'
  > C B
  > |/
  > A
  > EOF

  $ hg heads --template="{rev}:{node} {branch}: {desc}\n"
  2:dc0947a82db884575bb76ea10ac97b08536bfa03 default: C
  1:112478962961147124edd43549aedd1a335e44bf default: B

  $ hg strip C
  saved backup bundle to $TESTTMP/f/.hg/strip-backup/dc0947a82db8-d21b92a4-backup.hg

  $ hg tglog
  o  1: 112478962961 'B'
  |
  o  0: 426bada5c675 'A'
  


  $ hg heads --template="{rev}:{node} {branch}: {desc}\n"
  1:112478962961147124edd43549aedd1a335e44bf default: B

  $ cd ..

Test collapsing changes that add then remove a file

  $ hg init collapseaddremove
  $ cd collapseaddremove

  $ touch base
  $ hg commit -Am base
  adding base
  $ touch a
  $ hg commit -Am a
  adding a
  $ hg rm a
  $ touch b
  $ hg commit -Am b
  adding b
  $ hg book foo
  $ hg rebase -d 0 -r "1::2" --collapse -m collapsed
  rebasing 1:6d8d9f24eec3 "a"
  rebasing 2:1cc73eca5ecc "b" (foo tip)
  saved backup bundle to $TESTTMP/collapseaddremove/.hg/strip-backup/6d8d9f24eec3-77d3b6e2-rebase.hg
  $ hg log -G --template "{rev}: '{desc}' {bookmarks}"
  @  1: 'collapsed' foo
  |
  o  0: 'base'
  
  $ hg manifest --rev tip
  b
  base

  $ cd ..

Test that rebase --collapse will remember message after
running into merge conflict and invoking rebase --continue.

  $ hg init collapse_remember_message
  $ cd collapse_remember_message
  $ hg debugdrawdag << 'EOF'
  > C B # B/A = B\n
  > |/  # C/A = C\n
  > A
  > EOF
  $ hg rebase --collapse -m "new message" -b B -d C
  rebasing 1:81e5401e4d37 "B" (B)
  merging A
  warning: conflicts while merging A! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]
  $ rm A.orig
  $ hg resolve --mark A
  (no more unresolved files)
  continue: hg rebase --continue
  $ hg rebase --continue
  rebasing 1:81e5401e4d37 "B" (B)
  saved backup bundle to $TESTTMP/collapse_remember_message/.hg/strip-backup/81e5401e4d37-96c3dd30-rebase.hg
  $ hg log
  changeset:   2:17186933e123
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     new message
  
  changeset:   1:043039e9df84
  tag:         C
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     C
  
  changeset:   0:426bada5c675
  tag:         A
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     A
  
  $ cd ..

Test aborted editor on final message

  $ HGMERGE=:merge3
  $ export HGMERGE
  $ hg init aborted-editor
  $ cd aborted-editor
  $ hg debugdrawdag << 'EOF'
  > C   # D/A = D\n
  > |   # C/A = C\n
  > B D # B/A = B\n
  > |/  # A/A = A\n
  > A
  > EOF
  $ hg rebase --collapse -t internal:merge3 -s B -d D
  rebasing 1:f899f3910ce7 "B" (B)
  merging A
  warning: conflicts while merging A! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]
  $ hg tglog
  o  3: 63668d570d21 'C'
  |
  | @  2: 82b8abf9c185 'D'
  | |
  @ |  1: f899f3910ce7 'B'
  |/
  o  0: 4a2df7238c3b 'A'
  
  $ cat A
  <<<<<<< dest:   82b8abf9c185 D - test: D
  D
  ||||||| base
  A
  =======
  B
  >>>>>>> source: f899f3910ce7 B - test: B
  $ echo BC > A
  $ hg resolve -m
  (no more unresolved files)
  continue: hg rebase --continue
  $ hg rebase --continue
  rebasing 1:f899f3910ce7 "B" (B)
  rebasing 3:63668d570d21 "C" (C tip)
  merging A
  warning: conflicts while merging A! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]
  $ hg tglog
  @  3: 63668d570d21 'C'
  |
  | @  2: 82b8abf9c185 'D'
  | |
  o |  1: f899f3910ce7 'B'
  |/
  o  0: 4a2df7238c3b 'A'
  
  $ cat A
  <<<<<<< dest:   82b8abf9c185 D - test: D
  BC
  ||||||| base
  B
  =======
  C
  >>>>>>> source: 63668d570d21 C tip - test: C
  $ echo BD > A
  $ hg resolve -m
  (no more unresolved files)
  continue: hg rebase --continue
  $ HGEDITOR=false hg rebase --continue --config ui.interactive=1
  already rebased 1:f899f3910ce7 "B" (B) as 82b8abf9c185
  rebasing 3:63668d570d21 "C" (C tip)
  abort: edit failed: false exited with status 1
  [255]
  $ hg tglog
  o  3: 63668d570d21 'C'
  |
  | @  2: 82b8abf9c185 'D'
  | |
  o |  1: f899f3910ce7 'B'
  |/
  o  0: 4a2df7238c3b 'A'
  
  $ hg rebase --continue
  already rebased 1:f899f3910ce7 "B" (B) as 82b8abf9c185
  already rebased 3:63668d570d21 "C" (C tip) as 82b8abf9c185
  saved backup bundle to $TESTTMP/aborted-editor/.hg/strip-backup/f899f3910ce7-7cab5e15-rebase.hg