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.
resolving manifests
overwrite None partial False
ancestor 310fd17130da local 2092631ce82b+ remote 7731dad1c2b9
searching for copies back to rev 1
unmatched files in other:
bar
all copies found (* = to merge, ! = divergent):
bar -> foo *
checking for directory renames
foo: versions differ -> m
foo: remote copied to bar -> m
copying foo to bar
merging foo and bar
my foo@2092631ce82b+ other bar@7731dad1c2b9 ancestor foo@310fd17130da
merging foo
my foo@2092631ce82b+ other foo@7731dad1c2b9 ancestor foo@310fd17130da
0 files updated, 2 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
-- foo --
line 0
line 1
line 2-1
-- bar --
line 0
line 1
line 2-2