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 basic functionality of url#rev syntax
hg init repo
cd repo
echo a > a
hg ci -qAm 'add a' -d '0 0'
hg branch foo
echo >> a
hg ci -m 'change a' -d '0 0'
cd ..
echo '% clone repo#foo'
hg clone 'repo#foo' clone
echo '% heads'
hg --cwd clone heads
echo '% parents'
hg --cwd clone parents
sed -e 's/default.*#/default = #/' clone/.hg/hgrc
echo
echo '% changing original repo'
cd repo
echo >> a
hg ci -m 'new head of branch foo' -d '0 0'
hg up -qC default
echo bar > bar
hg ci -qAm 'add bar' -d '0 0'
hg log
echo
echo '% outgoing'
hg -q outgoing '../clone#foo'
echo
echo '% push'
hg -q push '../clone#foo'
hg --cwd ../clone heads
cd ..
echo
echo '% rolling back'
cd clone
hg rollback
echo '% incoming'
hg -q incoming
echo '% pull'
hg -q pull
hg heads
echo
echo '% pull should not have updated'
hg parents -q
echo '% going back to the default branch'
hg up -C 0
hg parents
echo '% no new revs, no update'
hg pull -qu
hg parents -q
echo '% rollback'
hg rollback
hg up -C 0
hg parents -q
echo '% pull -u takes us back to branch foo'
hg pull -qu
hg parents
echo '% rollback'
hg rollback
hg up -C 0
echo '% parents'
hg parents -q
echo '% heads'
hg heads -q
echo '% pull -u -r otherrev url#rev updates to rev'
hg pull -qur default default
echo '% parents'
hg parents
echo '% heads'
hg heads