revlog: add a comment to help clang-format produce less-awful results Differential Revision: https://phab.mercurial-scm.org/D5232

py3: ratchet caught two more passing tests Differential Revision: https://phab.mercurial-scm.org/D5236

perf: add a lazydeltabase option to perfrevlogwrite The option controls if we'll test the provided delta first. This is the current default behavior for unbundle.

perf: add `storage` as possible source for perfrevlogwrite This source will use the stored delta.

perf: add `parent-smallest` as possible source for perfrevlogwrite This source will use the smallest of the possible diff against parent.

perf: add `parent-2` as possible source for perfrevlogwrite This source will use a diff against p2 if it exists and fall back to p1 otherwise.

perf: add `parent-1` as possible source for perfrevlogwrite This source will use a diff against p1 in all case.

perf: add the notion of "source" to perfrevlogwrite We want to test performance associated witch various way to add a new revision. They will be specified using this new argument.

perf: only display the total time for perfrevlogwrite if quiet This provide a simple way to get an overview of the total performance.

perf: offer full details in perfrevlogwrite This will be useful for people who want to study the timing pattern more closely.