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

cp "$TESTDIR"/printenv.py .

hg init test
cd test
echo foo>foo
hg commit -A -d '0 0' -m 1
hg --config server.uncompressed=True serve -p 20059 -d --pid-file=../hg1.pid
hg serve -p 20060 -d --pid-file=../hg2.pid
# Test server address cannot be reused
hg serve -p 20060 2>&1 | sed -e 's/abort: cannot start server:.*/abort: cannot start server:/'
cd ..
cat hg1.pid hg2.pid >> $DAEMON_PIDS

echo % clone via stream
http_proxy= hg clone --uncompressed http://localhost:20059/ copy 2>&1 | \
  sed -e 's/[0-9][0-9.]*/XXX/g' -e 's/[KM]\(B\/sec\)/X\1/'
hg verify -R copy

echo % try to clone via stream, should use pull instead
http_proxy= hg clone --uncompressed http://localhost:20060/ copy2

echo % clone via pull
http_proxy= hg clone http://localhost:20059/ copy-pull
hg verify -R copy-pull

cd test
echo bar > bar
hg commit -A -d '1 0' -m 2
cd ..

echo % pull
cd copy-pull
echo '[hooks]' >> .hg/hgrc
echo 'changegroup = python ../printenv.py changegroup' >> .hg/hgrc
hg pull
cd ..