revlog: don't cache parsed tuples in the C module A cached entry creates ~8 Python objects per cached changeset, which comes to around 200 Bytes per cached changeset on AMD64. Especially for operations that touch a lot of changesets, that can easily sum up to more than a 100MB of memory. Simple tests on large repositories show <2% runtime penalty for ripping out the cache, even for cache heavy operations like "hg log" for all revisions. Differential Revision: https://phab.mercurial-scm.org/D9155