sync: fix --tags option

This has been broken since it was added where --tags was actually
the same as --no-tags.  Oddly, it was copied from init where the
logic is correct.

Bug: https://crbug.com/gerrit/12401
Change-Id: I15b89da1a655176a11bebc22573b25c728055328
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/322955
Reviewed-by: Andrew Lamb <andrewlamb@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
diff --git a/subcmds/sync.py b/subcmds/sync.py
index c230323..d4e302a 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -238,12 +238,11 @@
     p.add_option('--no-use-superproject', action='store_false',
                  dest='use_superproject',
                  help='disable use of manifest superprojects')
-    p.add_option('--tags',
-                 action='store_false',
+    p.add_option('--tags', action='store_true',
                  help='fetch tags')
     p.add_option('--no-tags',
                  dest='tags', action='store_false',
-                 help="don't fetch tags")
+                 help="don't fetch tags (default)")
     p.add_option('--optimized-fetch',
                  dest='optimized_fetch', action='store_true',
                  help='only fetch projects fixed to sha1 if revision does not exist locally')