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.
#!/bin/sh
HGMERGE=true; export HGMERGE
set -e
mkdir r1
cd r1
hg init
echo a > a
hg addremove
hg commit -m "1" -d "1000000 0"
hg clone . ../r2
cd ../r2
hg up
echo abc > a
hg diff --nodates
cd ../r1
echo b > b
echo a2 > a
hg addremove
hg commit -m "2" -d "1000000 0"
cd ../r2
hg -q pull ../r1
hg status
hg parents
hg --debug up
hg parents
hg --debug up 0
hg parents
hg --debug merge || echo failed
hg parents
hg --debug up
hg parents
hg -v history
hg diff --nodates
# create a second head
cd ../r1
hg up 0
echo b2 > b
echo a3 > a
hg addremove
hg commit -m "3" -d "1000000 0"
cd ../r2
hg -q pull ../r1
hg status
hg parents
hg --debug up || echo failed
hg --debug merge || echo failed
hg --debug merge -f
hg parents
hg diff --nodates
# test a local add
cd ..
hg init a
hg init b
echo a > a/a
echo a > b/a
hg --cwd a commit -A -m a
cd b
hg add a
hg pull -u ../a
hg st