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

hg init t
cd t
hg branches

echo foo > a
hg add a
hg ci -m "initial" -d "1000000 0"
hg branch foo
hg branch
hg ci -m "add branch name" -d "1000000 0"
hg branch bar
hg ci -m "change branch name" -d "1000000 0"
echo % branch shadowing
hg branch default
hg branch -f default
hg ci -m "clear branch name" -d "1000000 0"

hg co foo
hg branch
echo bleah > a
hg ci -m "modify a branch" -d "1000000 0"

hg merge
hg branch
hg ci -m "merge" -d "1000000 0"
hg log

hg branches
hg branches -q

echo % test for invalid branch cache
hg rollback
cp .hg/branch.cache .hg/bc-invalid
hg log -r foo
cp .hg/bc-invalid .hg/branch.cache
hg --debug log -r foo
rm .hg/branch.cache
echo corrupted > .hg/branch.cache
hg log -qr foo
cat .hg/branch.cache

echo % update with no arguments: tipmost revision of the current branch
hg up -q -C 0
hg up -q
hg id
hg up -q 1
hg up -q
hg id
hg branch foobar
hg up

echo % fastforward merge
hg branch ff
echo ff > ff
hg ci -Am'fast forward' -d '1000000 0'
hg up foo
hg merge ff
hg branch
hg commit -m'Merge ff into foo' -d '1000000 0'
hg parents
hg manifest

exit 0