test-convert-svn-branches: filter unwanted output
Windows cmd.exe emits a different message than sh:
"""
foobar is not recognized as an internal or external command,
operable program or batch file.
"""
Filter it.
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.