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.
hgrc settings command line options final result
quiet verbo debug quiet verbo debug quiet verbo debug
0 False False False False False False -> False False False
1 True False False False False False -> True False False
2 False True False False False False -> False True False
3 True True False False False False -> False False False
4 False False True False False False -> False True True
5 True False True False False False -> False True True
6 False True True False False False -> False True True
7 True True True False False False -> False True True
8 False False False True False False -> True False False
9 True False False True False False -> True False False
10 False True False True False False -> True False False
11 True True False True False False -> True False False
12 False False True True False False -> True False False
13 True False True True False False -> True False False
14 False True True True False False -> True False False
15 True True True True False False -> True False False
16 False False False False True False -> False True False
17 True False False False True False -> False True False
18 False True False False True False -> False True False
19 True True False False True False -> False True False
20 False False True False True False -> False True False
21 True False True False True False -> False True False
22 False True True False True False -> False True False
23 True True True False True False -> False True False
24 False False False True True False -> False False False
25 True False False True True False -> False False False
26 False True False True True False -> False False False
27 True True False True True False -> False False False
28 False False True True True False -> False False False
29 True False True True True False -> False False False
30 False True True True True False -> False False False
31 True True True True True False -> False False False
32 False False False False False True -> False True True
33 True False False False False True -> False True True
34 False True False False False True -> False True True
35 True True False False False True -> False True True
36 False False True False False True -> False True True
37 True False True False False True -> False True True
38 False True True False False True -> False True True
39 True True True False False True -> False True True
40 False False False True False True -> False True True
41 True False False True False True -> False True True
42 False True False True False True -> False True True
43 True True False True False True -> False True True
44 False False True True False True -> False True True
45 True False True True False True -> False True True
46 False True True True False True -> False True True
47 True True True True False True -> False True True
48 False False False False True True -> False True True
49 True False False False True True -> False True True
50 False True False False True True -> False True True
51 True True False False True True -> False True True
52 False False True False True True -> False True True
53 True False True False True True -> False True True
54 False True True False True True -> False True True
55 True True True False True True -> False True True
56 False False False True True True -> False True True
57 True False False True True True -> False True True
58 False True False True True True -> False True True
59 True True False True True True -> False True True
60 False False True True True True -> False True True
61 True False True True True True -> False True True
62 False True True True True True -> False True True
63 True True True True True True -> False True True