rebase: choose merge base without unwanted revisions
Previously, when there are 2 merge base candidates, we choose p1 blindly,
which may make the merge result to have "unwanted content". This patch makes
rebase smarter - choose a merge base that does not have "unwanted revs" if
possible. Since we don't really have a good solution when there are
"unwanted revs", abort in that case.
Differential Revision: https://phab.mercurial-scm.org/D340
#require symlink
https://bz.mercurial-scm.org/1438
$ hg init
$ ln -s foo link
$ hg add link
$ hg ci -mbad link
$ hg rm link
$ hg ci -mok
$ hg diff -g -r 0:1 > bad.patch
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg import --no-commit bad.patch
applying bad.patch
$ hg status
R link
? bad.patch