tests: apply binary mode to output in seq.py I noticed this when playing with running tests using WSL, and iterating over the output yielded '0\r', '1\r',... Most of the other *.py tools do this, and `seq` on MSYS lacks '\r' in the output, so this is more consistent.

perf: add a `--clear-caches` to `perfbranchmapupdate` This flag will help to measure the time we spend loading various cache that support the branchmap update. Example for an 500 000 revisions repository: hg perfbranchmapupdate --base 'not tip' --target 'tip' ! wall 0.000860 comb 0.000000 user 0.000000 sys 0.000000 (best of 336) hg perfbranchmapupdate --base 'not tip' --target 'tip' --clear-caches ! wall 0.029494 comb 0.030000 user 0.030000 sys 0.000000 (best of 100)

perf: start from an existing branchmap if possible If the --base set if a superset of one of the cached branchmap, we should use as a starting point. This greatly help the overall runtime of `hg perfbranchmapupdate` For example, for a repository with about 500 000 revisions, using this trick make the command runtime move from about 200 second to about 10 seconds. A 20x gain.