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.
checkout
2 files updated, 0 files merged, 2 files removed, 0 files unresolved
merge
resolving manifests
overwrite None partial False
ancestor af1939970a1c local f26ec4fc3fa3+ remote 8e765a822af2
searching for copies back to rev 1
unmatched files in local:
c2
unmatched files in other:
b
b2
all copies found (* = to merge, ! = divergent):
c2 -> a2
b -> a *
b2 -> a2
checking for directory renames
a2: divergent renames -> dr
a: remote moved to b -> m
b2: remote created -> g
copying a to b
merging a and b
my a@f26ec4fc3fa3+ other b@8e765a822af2 ancestor a@af1939970a1c
removing a
warning: detected divergent renames of a2 to:
c2
b2
getting b2
1 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
M b
a
M b2
R a
C c2
blahblah
rev offset length base linkrev nodeid p1 p2
0 0 67 0 1 dc51707dfc98 000000000000 000000000000
1 67 72 1 3 b2494a44f0a9 000000000000 dc51707dfc98
b renamed from a:dd03b83622e78778b403775d0d074b9ac7387a66