avoid negative variables

Trying to use booleans with names like "no_xxx" are hard to follow due
to the double negatives.  Invert all of them so we only have positive
meanings to follow.

Change-Id: Ifd37d0368f97034d94aa2cf38db52c723ac0c6ed
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/255493
Tested-by: Mike Frysinger <vapier@google.com>
Reviewed-by: David Pursehouse <dpursehouse@collab.net>

subcmds/selfupdate.py

@@ -40,7 +40,7 @@ need to be performed by an end-user.
   def _Options(self, p):
     g = p.add_option_group('repo Version options')
     g.add_option('--no-repo-verify',
-                 dest='no_repo_verify', action='store_true',
+                 dest='repo_verify', default=True, action='store_false',
                  help='do not verify repo source code')
     g.add_option('--repo-upgraded',
                  dest='repo_upgraded', action='store_true',
@@ -60,5 +60,5 @@ need to be performed by an end-user.
 
       rp.bare_git.gc('--auto')
       _PostRepoFetch(rp,
-                     no_repo_verify=opt.no_repo_verify,
+                     repo_verify=opt.repo_verify,
                      verbose=True)