sparse-revlog: rework the way we enforce chunk size limit We move from a O(N) algorithm to a O(log(N)) algorithm. The previous algorithm was traversing the whole delta chain, looking for the exact point where it became too big. This would result in most of the delta chain to be traversed. Instead, we now use a "binary" approach, slicing the chain in two until we have a chunk of the appropriate size. We still keep the previous algorithm for the snapshots part. There are few of them and they are large bits of data distant from each other. So the previous algorithm should work well in that case. To take a practical example of restoring manifest revision '59547c40bc4c' for a reference NetBeans repository (using sparse-revlog). The media time of the step `slice-sparse-chain` of `perfrevlogrevision` improve from 1.109 ms to 0.660 ms.

doctest: add a `issnapshot` method to _testrevlog We'll need it soon.

tests: add `revlogutils.deltas` module to doctests The doctest in these module have been from `mercurial.revlog` but the module was not added to the doctests. Spotted by Yuya Nishihara.

merge with stable

mergetools: adjust Beyond Compare config on Mac/Linux Set the labels of the Linux and Mac versions of Beyond Compare from Mercurial's builtin variables, same as the Windows version. Differential Revision: https://phab.mercurial-scm.org/D5255

tests: allow for 100% of profiled time in sleep in test-profile.t I'm getting an annoying failure in this test on our builder, and I *think* what's happening is that the profiler is taking _just_ long enough to start that we're spending 100% of the profiled time in the sleep function, which was causing the leading space to not be printed since the 100 was in the first column of output. Differential Revision: https://phab.mercurial-scm.org/D5272

rewriteutil: move publicrevs closer to where it's used

requires: use atomictemp=True when writing .hg/requires We use an unusual file system at Google that allows writes (and renames) but not deletions (for certain paths). That causes problems when writing the requires files without atomictemp=True. There doesn't appear to be any real drawbacks to using atomictemp, so I'm hoping we can just change it in core. Differential Revision: https://phab.mercurial-scm.org/D5274

blackbox: extract _log() function which is called after lastui is resolved This makes sure that self is the solo ui instance used in _log().

blackbox: inline temporary variables which are referenced only once