convert: fix mercurial_sink.putcommit
Changeset 4ebc8693ce72 added some code to putcommit to avoid creating a
revision that touches no files, but this can break regular conversions
from some repositories:
- conceptually, since we're converting a repo, we should try to make
the new hg repo as similar as possible to the original repo - we
should create a new changeset, even if the original revision didn't
touch any files (maybe the commit message had some important bit);
- even if a "regular" revision that doesn't touch any file may seem
weird (and maybe even broken), it's completely legitimate for a merge
revision to not touch any file, and, if we just skip it, the
converted repo will end up with wrong history and possibly an extra
head.
As an example, say the crew and main hg repos are sync'ed. Somebody
sends an important patch to the mailing list. Matt quickly applies
and pushes it. But at the same time somebody also applies it to crew
and pushes it. Suppose the commit message ended up being a bit
different (say, there was a typo and somebody didn't fix it) or that
the date ended up being different (because of different patch-applying
scripts): the changeset hashes will be different, but the manifests
will be the same.
Since both changesets were pushed to public repos, it's hard to recall
them. If both are merged, the manifest from the resulting merge
revision will have the exact same contents as its parents - i.e. the
merge revision really doesn't touch any file at all.
To keep the file filtering stuff "working", the generic code was changed
to skip empty revisions if we're filtering the repo, fixing a bug in the
process (we want parents[0] instead of tip).
#!/bin/sh
hg init
echo "# revision 0"
echo "unchanged" > unchanged
echo "remove me" > remove
echo "copy me" > copy
echo "move me" > move
for i in 1 2 3 4 5 6 7 8 9; do
echo "merge ok $i" >> zzz1_merge_ok
done
echo "merge bad" > zzz2_merge_bad
hg ci -Am "revision 0" -d "1000000 0"
echo "# revision 1"
hg rm remove
hg mv move moved
hg cp copy copied
echo "added" > added
hg add added
echo "new first line" > zzz1_merge_ok
hg cat zzz1_merge_ok >> zzz1_merge_ok
echo "new last line" >> zzz2_merge_bad
hg ci -m "revision 1" -d "1000000 0"
echo "# local changes to revision 0"
hg co 0
echo "new last line" >> zzz1_merge_ok
echo "another last line" >> zzz2_merge_bad
hg diff --nodates | grep "^[+-][^<>]"
hg st
echo "# local merge with bad merge tool"
HGMERGE=false hg co
hg co 0
hg diff --nodates | grep "^[+-][^<>]"
hg st
echo "# local merge with conflicts"
hg co
hg co 0
hg diff --nodates | grep "^[+-][^<>]"
hg st
echo "# local merge without conflicts"
hg revert zzz2_merge_bad
hg co
hg diff --nodates | grep "^[+-][^<>]"
hg st