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.
$ hg init t
$ cd t
$ mkdir a
$ echo foo > a/a
$ echo bar > a/b
$ hg ci -Am "0"
adding a/a
adding a/b
$ hg co -C 0
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg mv a b
moving a/a to b/a (glob)
moving a/b to b/b (glob)
$ hg ci -m "1 mv a/ b/"
$ hg co -C 0
2 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ echo baz > a/c
$ echo quux > a/d
$ hg add a/c
$ hg ci -m "2 add a/c"
created new head
$ hg merge --debug 1
searching for copies back to rev 1
unmatched files in local:
a/c
unmatched files in other:
b/a
b/b
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'a/a' -> dst: 'b/a'
src: 'a/b' -> dst: 'b/b'
checking for directory renames
discovered dir src: 'a/' -> dst: 'b/'
pending file src: 'a/c' -> dst: 'b/c'
resolving manifests
overwrite: False, partial: False
ancestor: f9b20c0d4c51, local: ce36d17b18fb+, remote: 397f8b00a740
a/a: other deleted -> r
a/b: other deleted -> r
a/c: remote renamed directory to b/c -> d
b/a: remote created -> g
b/b: remote created -> g
updating: a/a 1/5 files (20.00%)
removing a/a
updating: a/b 2/5 files (40.00%)
removing a/b
updating: a/c 3/5 files (60.00%)
moving a/c to b/c
updating: b/a 4/5 files (80.00%)
getting b/a
updating: b/b 5/5 files (100.00%)
getting b/b
3 files updated, 0 files merged, 2 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ echo a/* b/*
a/d b/a b/b b/c
$ hg st -C
M b/a
M b/b
A b/c
a/c
R a/a
R a/b
R a/c
? a/d
$ hg ci -m "3 merge 2+1"
$ hg debugrename b/c
b/c renamed from a/c:354ae8da6e890359ef49ade27b68bbc361f3ca88 (glob)
$ hg co -C 1
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg merge --debug 2
searching for copies back to rev 1
unmatched files in local:
b/a
b/b
unmatched files in other:
a/c
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'a/a' -> dst: 'b/a'
src: 'a/b' -> dst: 'b/b'
checking for directory renames
discovered dir src: 'a/' -> dst: 'b/'
pending file src: 'a/c' -> dst: 'b/c'
resolving manifests
overwrite: False, partial: False
ancestor: f9b20c0d4c51, local: 397f8b00a740+, remote: ce36d17b18fb
None: local renamed directory to b/c -> d
updating:None 1/1 files (100.00%)
getting a/c to b/c
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ echo a/* b/*
a/d b/a b/b b/c
$ hg st -C
A b/c
a/c
? a/d
$ hg ci -m "4 merge 1+2"
created new head
$ hg debugrename b/c
b/c renamed from a/c:354ae8da6e890359ef49ade27b68bbc361f3ca88 (glob)
Second scenario with two repos:
$ cd ..
$ hg init r1
$ cd r1
$ mkdir a
$ echo foo > a/f
$ hg add a
adding a/f (glob)
$ hg ci -m "a/f == foo"
$ cd ..
$ hg clone r1 r2
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd r2
$ hg mv a b
moving a/f to b/f (glob)
$ echo foo1 > b/f
$ hg ci -m" a -> b, b/f == foo1"
$ cd ..
$ cd r1
$ mkdir a/aa
$ echo bar > a/aa/g
$ hg add a/aa
adding a/aa/g (glob)
$ hg ci -m "a/aa/g"
$ hg pull ../r2
pulling from ../r2
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg merge
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg st -C
M b/f
A b/aa/g
a/aa/g
R a/aa/g
R a/f
$ cd ..