changegroup: restore original behavior of _nextclrevtolocalrev 0548f696795b accidentally changed the behavior of cgpacker._close(). The old behavior moved _nextclrevtolocalrev to _clrevtolocalrev only when _nextclrevtolocalrev was present and then removed _nextclrevtolocalrev. The bad behavior performed this move then cleared _clrevtolocalrev because it was the same object as _nextclrevtolocalrev. This commit restores the previous behavior. Surprisingly, no tests changed as a result of this bad logic. I'm not sure why. Differential Revision: https://phab.mercurial-scm.org/D4155

py3: whitelist another test caught by the ratchet Differential Revision: https://phab.mercurial-scm.org/D4173

debugcommands: force import of fileset in debugfileset It looks like Python 3's lazy importer is better than Python 2's for this command, and as a result we had no symbols in the filesetlang symbol table, which resulted in some really mysterious test-fileset.t failures around withstatus optimizations. Inserting this explicit import and forcing its evaluation fixes the test failure. Differential Revision: https://phab.mercurial-scm.org/D4172

linelog: optimize replacelines The optimization to avoid calling `annotate` inside `replacelines` is significant for practical use patterns. Before this patch: hg perflinelogedits ! wall 6.778478 comb 6.710000 user 6.700000 sys 0.010000 (best of 3) After this patch: hg perflinelogedits ! wall 0.136573 comb 0.140000 user 0.130000 sys 0.010000 (best of 63) Differential Revision: https://phab.mercurial-scm.org/D4150

linelog: extract `len(self._program)` to a local function This is a micro optimization prepared for following changes where `len(self._program)` is used in a loop. Differential Revision: https://phab.mercurial-scm.org/D4149

perf: add a command to benchmark linelog edits The use pattern of creating a linelog is usually by calling "replacelines" multiple times. Add a command to benchmark it. Differential Revision: https://phab.mercurial-scm.org/D4148