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

cat > patchtool.py <<EOF
import sys
print 'Using custom patch'
if '--binary' in sys.argv:
    print '--binary found !'
EOF

echo "[ui]" >> $HGRCPATH
echo "patch=python ../patchtool.py" >> $HGRCPATH

hg init a
cd a
echo a > a
hg commit -Ama -d '1 0'
echo b >> a
hg commit -Amb -d '2 0'
cd ..

# This test check that:
# - custom patch commands with arguments actually works
# - patch code does not try to add weird arguments like
# --binary when custom patch commands are used. For instance
# --binary is added by default under win32.

echo % check custom patch options are honored
hg --cwd a export -o ../a.diff tip
hg clone -r 0 a b

hg --cwd b import -v ../a.diff