Add searching for named branches named branching is when you identify a head by a tag on an earlier revision. This patch adds repo.branchlookup for searching through the tree to find branch tags for heads. hg update -b tag is added to checkout based on branch tags hg heads -b is added to print the tag associated with each head

\.orig$
\.rej$
~$
\.so$
\.pyc$
\.swp$
\.prof$
^tests/.*\.err$
^build/
^dist/
^doc/.*\.[0-9](\.(x|ht)ml)?$
^MANIFEST$
^\.pc/
^patches/
^mercurial/__version__.py$