convert: add a mode where mercurial_sink skips empty revisions.
The getchanges function of some converter_source classes can return
some false positives. I.e. they sometimes claim that a file "foo"
was changed in some revision, even though its contents are still the
same.
convert_svn is particularly bad, but I think this can also happen with
convert_cvs and, at least in theory, with mercurial_source.
For regular conversions this is not really a problem - as long as
getfile returns the right contents, we'll get a converted revision
with the right contents. But when we use --filemap, this could lead
to superfluous revisions being converted.
Instead of fixing every converter_source, I decided to change
mercurial_sink to work around this problem.
When --filemap is used, we're interested only in revisions that touch
some specific files. If a revision doesn't change any of these files,
then we're not interested in it (at least for revisions with a single
parent; merges are special).
For mercurial_sink, we abuse this property and rollback a commit if
the manifest text hasn't changed. This avoids duplicating the logic
from localrepo.filecommit to detect unchanged files.
1 files updated, 0 files merged, 2 files removed, 0 files unresolved
resolving manifests
overwrite None partial False
ancestor 583c7b748052 local fb3948d97f07+ remote 40da226db0f0
searching for copies back to rev 1
unmatched files in other:
b
c
all copies found (* = to merge, ! = divergent):
c -> a *
b -> a *
checking for directory renames
a: remote moved to c -> m
a: remote moved to b -> m
copying a to b
copying a to c
merging a and b
my a@fb3948d97f07+ other b@40da226db0f0 ancestor a@583c7b748052
removing a
merging a and c
my a@fb3948d97f07+ other c@40da226db0f0 ancestor a@583c7b748052
0 files updated, 2 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
-- b --
0
1
2
-- c --
0
1
2