revsetbenchmark: support for running on other repo We add a -R/--repo option to run the benchmarks on another repository. This is very useful as some repository are bigger/more interesting than the mercurial one.

revsetbenchmark: automatically finds the perf extension Before this changeset, you had to stand in the root of the mercurial repo to run the `revsetbenchmark.py` script. Otherwise, the perf extension would not be found a `./contrib/perf.py` and the script would crash in panic. We now figure out the contrib directory from the location of this script. This makes it possible to run the script from other location that the mercurial repo root (but you still need to be in the core mercurial repository)

bundle2: make sure standard stream are binary Python on Windows apparently use encoded stream by default. We use the same trick than elsewhere in the code to make them binary. This should fix the current buildbot failure on windows.

revset-benchmark: add max(::(tip~20) - obsolete()) This revset is used in evolve. The new revset lazyness should make it all faster but in practice it is significantly slower. Below is a timing for this entry on my Mercurial repo. 2.9.2) ! wall 0.034598 comb 0.040000 user 0.040000 sys 0.000000 (best of 100) 3.0+@) ! wall 0.062268 comb 0.060000 user 0.060000 sys 0.000000 (best of 100) The ~20 have been taken arbitrary.