revlog: add some direct testing of the slicing logic This test check slicing backed by an actual revlog. It will test the C version of slicing (if the test are run with the C extensions).

revlog: limit base to rev size ratio to 500 instead of 50 While a value of 50 provided large speedup in some case (400s → 7s) it also creates a slow down for a whole class of revision we are seeing in a private repository (0.1s → 3s). A value of 500 makes them disappear improving the total runtime (the slower revision still improve significantly (400s → 21s)). We need to run a wider array of tests on various repositories to see the effect on speed and size of different values for this acceptable constant. However, in the meantime, it seems safer to move back to a less impactful value.

contrib: remove unused version of os Caught by test-check-pyflakes.t Differential Revision: https://phab.mercurial-scm.org/D5471

py3: convert `'{}'.format(foo)` to `'%s' % foo` in the bookflow extension Byte strings don't have the former. Converting these to byte strings is waiting on the mass rewrite.

py3: byteify sys.argv in gendoc.py

repository: update interface signature of narrowmatch() This should have been part of 4fd0fac48922 (localrepo: allow narrowmatch() to accept matcher to intersect with, 2018-09-28) and 41fcdfe3bfeb (narrow: allow repo.narrowmatch(match) to include exact matches from "match", 2018-10-01). Differential Revision: https://phab.mercurial-scm.org/D5466

narrow: when narrowing, write new narrowspec before removing revlogs If revlogs were removed and then the process crashed before the narrowspec was written, the repo would be corrupt. Differential Revision: https://phab.mercurial-scm.org/D5467