test-patch-offset: Don't use unified diff
Solaris diff -u likes to be "helpful" and tell that "No differences encountered"
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
See http://mercurial.selenic.com/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.