convert: svn -- fix 'exists'
Previously 'exists' erroneously returned False for empty dirictories. This is
wrong since we want to detect even empty 'branches/' or 'tags/'.
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
See http://www.selenic.com/mercurial/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.