blackbox: only show new heads on incoming
The blackbox was logging every head after every incoming group.
Now we only log the heads that have changed.
Added a test. Moved the hooks test to the bottom of the file since
the hooks interfer with the tests after it.
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.