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" cvs cvsps || exit 80

echo "[extensions]" >> $HGRCPATH
echo "convert = " >> $HGRCPATH

echo % create cvs repository
mkdir cvsrepo
cd cvsrepo
export CVSROOT=`pwd`
cd ..

cvs -q -d "$CVSROOT" init

echo % create source directory
mkdir src-temp
cd src-temp
echo a > a
mkdir b
cd b
echo c > c
cd ..

echo % import source directory
cvs -q import -m import src INITIAL start
cd ..

echo % checkout source directory
cvs -q checkout src

echo % convert fresh repo
hg convert src src-hg | sed -e 's/connecting to.*cvsrepo/connecting to cvsrepo/g'
cat src-hg/a
cat src-hg/b/c

echo % commit new file revisions
cd src
echo a >> a
echo c >> b/c
cvs -q commit -mci1 . | grep '<--' |\
    sed -e 's:.*src/\(.*\),v.*:checking in src/\1,v:g'
cd ..

echo % convert again
hg convert src src-hg | sed -e 's/connecting to.*cvsrepo/connecting to cvsrepo/g'
cat src-hg/a
cat src-hg/b/c