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

linelog: update internal help text This clarifies the details asked by @martinvonz on D3990. Differential Revision: https://phab.mercurial-scm.org/D4147

fix: determine fixer tool failure by exit code instead of stderr This seems like the more natural thing, and it probably should have been this way to beign with. It is more flexible because it allows tools to emit diagnostic information while also modifying a file. An example would be an automatic code formatter that also prints any remaining lint issues. Differential Revision: https://phab.mercurial-scm.org/D4158