heads: add support for specifying branches by revset
Before this commit, e.g. "hg heads .^" would fail with:
abort: unknown revision '.^'!
Like the previous patch, I don't care about the command itself (I
don't think I had ever used it before), I'm just cleaning up uses of
repo[<string>].
Differential Revision: https://phab.mercurial-scm.org/D3084
Mercurial
=========
Mercurial is a fast, easy to use, distributed revision control tool
for software developers.
Basic install::
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing::
$ make local # build for inplace usage
$ ./hg --version # should show the latest version
See https://mercurial-scm.org/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.