convert: keep branch switching merges with ancestors (issue3340)
When running convert with a filemap, merge parents which are ancestors
of other parents are ignored. This is hardly a problem when parents
belong to the same branch, but the result could be confusing when named
branches are involved. With:
-o-a1-a2-a3... <- A
\ \
b1-b2-b3...-m- <- B
If all b* revisions are discarded, it is useful to preserve 'm' even if
it is empty after filtering to record the branch switch.
This patch makes filemap preserve "ancestor parents" if there is no
"non-ancestor parent" on the same branch than the merge revision.
Remarks:
- I am not completely convinced by the reasons given above and those
detailed by Matt in this thread:
http://selenic.com/pipermail/mercurial-devel/2012-May/040627.html
The properties we try to preserve are not clearly defined. That said,
I know this patch already helped someone on IRC and the tests output
look reasonable.
- This is a new version of the original "convert: filemap must preserve
fast-forward merges" patch. It has exactly the same output for 2
parents merges, the additional complexity is here to handle more than
two parents.
Test for changeset 9fe267f77f56ff127cf7e65dc15dd9de71ce8ceb
(merge correctly when all the files in a directory are moved
but then local changes are added in the same directory)
$ hg init a
$ cd a
$ mkdir -p testdir
$ echo a > testdir/a
$ hg add testdir/a
$ hg commit -m a
$ cd ..
$ hg clone a b
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd a
$ echo alpha > testdir/a
$ hg commit -m remote-change
$ cd ..
$ cd b
$ mkdir testdir/subdir
$ hg mv testdir/a testdir/subdir/a
$ hg commit -m move
$ mkdir newdir
$ echo beta > newdir/beta
$ hg add newdir/beta
$ hg commit -m local-addition
$ hg pull ../a
pulling from ../a
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 up -C 2
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg merge
merging testdir/subdir/a and testdir/a to testdir/subdir/a
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg stat
M testdir/subdir/a
$ hg diff --nodates
diff -r bc21c9773bfa testdir/subdir/a
--- a/testdir/subdir/a
+++ b/testdir/subdir/a
@@ -1,1 +1,1 @@
-a
+alpha
$ cd ..