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

"$TESTDIR/hghave" no-symlink || exit 80

# The following script was used to create the bundle:
#
# hg init symlinks
# cd symlinks
# echo a > a
# mkdir d
# echo b > d/b
# ln -s a a.lnk
# ln -s d/b d/b.lnk
# hg ci -Am t
# hg bundle --base null ../test-no-symlinks.hg

# Extract a symlink on a platform not supporting them
echo % unbundle
hg init t
cd t
hg pull -q "$TESTDIR/test-no-symlinks.hg"
hg update

cat a.lnk && echo
cat d/b.lnk && echo

# Copy a symlink and move another
echo % move and copy
hg copy a.lnk d/a2.lnk
hg mv d/b.lnk b2.lnk
hg ci -Am copy
cat d/a2.lnk && echo
cat b2.lnk && echo

# Bundle and extract again
echo % bundle
hg bundle --base null ../symlinks.hg
cd ..

hg init t2
cd t2
hg pull ../symlinks.hg
hg update

cat a.lnk && echo
cat d/a2.lnk && echo
cat b2.lnk && echo