rebase: do not invent successor to skipped changeset
When rebase results in an empty a changeset it is "skipped" and no related
changeset is created at all. When we added obsolescence support to rebase (in
fc2a6114f0a0) it seemed a good idea to use its parent successor as the
successors for such dropped changesets. (see old version of the altered test).
This option was chosen because it seems a good way to hint about were the
dropped changeset "intended" to be. Such hint would have been used by automatic
evolution mechanism to rebase potential unstable children.
However, field testing of this version are not conclusive. It very often leads
to the creation of (totally unfounded) evolution divergence. This changeset
changes this behavior and mark skipped changesets as pruned (obsolete without
successors). This prevents the issue and seems semantically better probably a
win for obsolescence reading tool.
See example bellow for details:
User Babar has five changesets of interest:
- O, its current base of development.
- U, the new upstream
- A and C, some development changesets
- B another development changeset independent from A
O - A - B - C
\
U
Babar decides that B is more critical than the A and C and rebase it first
$ hg rebase --rev B --dest U
B is now obsolete (in lower case bellow). Rebase result, B', is its
successors.(note, C is unstable)
O - A - b - C
\
U - B'
Babar is now done with B', and want to rebase the rest of its history:
$ hg rebase --source A --dest B'
hg rebase process A, B and C. B is skipped as all its changes are already contained
in B'.
O - U - B' - A' - C'
Babar have the expected result graph wise, obsolescence marker are as follow:
B -> B' (from first rebase)
A -> A' (from second rebase)
C -> C' (from second rebase)
B -> ?? (from second rebase)
Before this changeset, the last marker is `B -> A'`. This cause two issues:
- This is semantically wrong. B have nothing to do with A'
- B has now two successors sets: (B',) and (A',). We detect a divergent
rewriting. The B' and A' are reported as "divergent" to Babar, confusion
ensues. In addition such divergent situation (divergent changeset are children
to each other) is tricky to solve.
With this changeset the last marker is `B -> ΓΈ`:
- This is semantically better.
- B has a single successors set (B',)
This scenario is added to the tests suite.
$ . "$TESTDIR/histedit-helpers.sh"
$ cat >> $HGRCPATH <<EOF
> [extensions]
> graphlog=
> histedit=
> EOF
$ EDITED="$TESTTMP/editedhistory"
$ cat > $EDITED <<EOF
> drop 177f92b77385 c
> pick e860deea161a e
> pick 652413bf663e f
> pick 055a42cdd887 d
> EOF
$ initrepo ()
> {
> hg init r
> cd r
> for x in a b c d e f ; do
> echo $x > $x
> hg add $x
> hg ci -m $x
> done
> }
$ initrepo
log before edit
$ hg log --graph
@ changeset: 5:652413bf663e
| tag: tip
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: f
|
o changeset: 4:e860deea161a
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: e
|
o changeset: 3:055a42cdd887
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: d
|
o changeset: 2:177f92b77385
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: c
|
o changeset: 1:d2ae7f538514
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: b
|
o changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
edit the history
$ HGEDITOR="cat \"$EDITED\" > " hg histedit 177f92b77385 2>&1 | fixbundle
0 files updated, 0 files merged, 4 files removed, 0 files unresolved
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
log after edit
$ hg log --graph
@ changeset: 4:f518305ce889
| tag: tip
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: d
|
o changeset: 3:a4f7421b80f7
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: f
|
o changeset: 2:ee283cb5f2d5
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: e
|
o changeset: 1:d2ae7f538514
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: b
|
o changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
Check histedit_source
$ hg log --debug --rev f518305ce889
changeset: 4:f518305ce889c07cb5bd05522176d75590ef3324
tag: tip
phase: draft
parent: 3:a4f7421b80f79fcc59fff01bcbf4a53d127dd6d3
parent: -1:0000000000000000000000000000000000000000
manifest: 4:d3d4f51c157ff242c32ff745d4799aaa26ccda44
user: test
date: Thu Jan 01 00:00:00 1970 +0000
files+: d
extra: branch=default
extra: histedit_source=055a42cdd88768532f9cf79daa407fc8d138de9b
description:
d
manifest after edit
$ hg manifest
a
b
d
e
f
$ cd ..