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