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

# Test issue 529 - mq aborts when merging patch deleting files

rewrite_path()
{
    sed -e 's:\\:/:g' -e 's:[^ ]*/t/::g'
}

echo "[extensions]" >> $HGRCPATH
echo "hgext.mq=" >> $HGRCPATH

# Commit two dummy files in "init" changeset
hg init t
cd t
echo a > a
echo b > b
hg ci -Am init
hg tag -l init

# Create a patch removing a
hg qnew rm_a
hg rm a
hg qrefresh -m "rm a"

# Save the patch queue so we can merge it later
hg qsave -c -e 2>&1 | rewrite_path

# Update b and commit in an "update" changeset
hg up -C init
echo b >> b
hg st
hg ci -m update

# Here, qpush used to abort with :
# The system cannot find the file specified => a
hg manifest
hg qpush -a -m 2>&1 | rewrite_path
hg manifest

# ensure status is correct after merge
hg qpop -a