Add branchtags function with cache - cache stores tipmost node and rev and node,label pairs - if cache is out of date, scan new changesets - write new cache out after scan

#!/bin/sh

unset HGUSER
EMAIL="My Name <myname@example.com>"
export EMAIL

hg init test
cd test
touch asdf
hg add asdf
hg commit -d '1000000 0' -m commit-1
hg tip