verify: reference the correct linkrev when a filelog is missing
when a filelog is missing, the first bad revision is the first revision
where the filelog is referenced, not 0.
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.