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

+ hg init
+ hg add a
+ hg commit -m ancestor -d 0 0
+ hg commit -m branch1 -d 0 0
+ hg co 0
+ hg commit -m branch2 -d 0 0
+ hg up -m 1
merge: warning: conflicts during merge
merging a
merging a failed!
+ hg id
32e80765d7fe+75234512624c+ tip
something else
=======
something
+ hg status
M a