subrepo: add 'cat' support for git subrepos
V2: use 'self._ctx.node()' instead of 'rev' in makefileobj.
As Matt Harbison mentioned, using 'rev' does not make sense,
since we'd be passing a git revision to the top-level
Mercurial repository.
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 http://mercurial.selenic.com/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.