tags: defer tag validation until repo.tags() is called Before, we were validating all tags for any tag operation, which meant building a (nearly) full node->tag lookup tree for most operations.

parsers: fix a memleak, and add a clearcaches method to the index This change also fixes a nasty memory leak: previously, self->caches was not being freed. The new clearcaches method lets us benchmark with finer granularity, as it lets us separate the cost of loading a revlog index from those of populating and accessing the cache data structures.

hghave: remove symlink test made useless by ac0da5caebec