tests: make run-tests exit non-zero if there are "errors" Previously, if there was an error such as a broken .t file that caused run-tests.py to encounter an exception during parsing, the test would be considered in an "errored" state, which is separate from "failed". The check for whether to exit non-zero or not was based entirely on whether there were any tests in a "failed" state, so if there was only an error, run-tests would exit with 0. Our test infrastructure would then consider the test as passing, causing us to have some tests with false negatives that have gone undetected for a few weeks now. Differential Revision: https://phab.mercurial-scm.org/D6452

perf: add a `perfhelper-mergecopies` command This command gather data that are useful to pick argument for `perfmergecopies`.

perf: add a new `perfmergecopies` command This command benchmark calls to `mercurial.copies.mergecopies`

perf: factor selection of revisions involved in the merge out We will introduce more performance command around merge. As a first step we factor out pieces of `perfmergecalculate` that can be reused.

perf: allow to specify the base of the merge in perfmergecalculate We can now test the rebase case.

perf: add a --from flag to perfmergecalculate Before this change, `perfmergecalculate` was always benchmarking the merge of the working copy with another revision. We can now benchmark the `mergecalculate` call for any arbitrary pair of revision.

merge with stable

py3: fix test-narrow* which started failing because of recent changes #skip-blame because just r'' prefix Differential Revision: https://phab.mercurial-scm.org/D6447

manifest: add some documentation to _lazymanifest python code It was not particularly easy figuring out the design of this class and keeping track of how the pieces work. So might as well write some of it down for the next person.

manifest: avoid corruption by dropping removed files with pure (issue5801) Previously, removed files would simply be marked by overwriting the first byte with NUL and dropping their entry in `self.position`. But no effort was made to ignore them when compacting the dictionary into text form. This allowed them to slip into the manifest revision, since the code seems to be trying to minimize the string operations by copying as large a chunk as possible. As part of this, compact() walks the existing text based on entries in the `positions` list, and consumed everything up to the next position entry. This typically resulted in a ValueError complaining about unsorted manifest entries. Sometimes it seems that files do get dropped in large repos- it seems to correspond to there being a new entry that would take the same slot. A much more trivial problem is that if the only changes were removals, `_compact()` didn't even run because `__delitem__` doesn't add anything to `self.extradata`. Now there's an explicit variable to flag this, both to allow `_compact()` to run, and to avoid searching the manifest in cases where there are no removals. In practice, this behavior was mostly obscured by the check in fastdelta() which takes a different path that explicitly drops removed files if there are fewer than 1000 changes. However, timeless has a repo where after rebasing tens of commits, a totally different path[1] is taken that bypasses the change count check and hits this problem. [1] https://www.mercurial-scm.org/repo/hg/file/2338bdea4474/mercurial/manifest.py#l1511