merge with stable

merge with crew

tests: removed unneeded section in acl configuration: 'extensions' Declaring 'acl' in the [extensions] section doesn't change anything.

config: use util.compilere to compile regexps

matcher: use re2 bindings if available There are two sets of Python re2 bindings available on the internet; this code works with both. Using re2 can greatly improve "hg status" performance when a .hgignore file becomes even modestly complex. Example: "hg status" on a clean tree with 134K files, where "hg debugignore" reports a regexp 4256 bytes in size. no .hgignore: 1.76 sec Python re: 2.79 re2: 1.82 The overhead of regexp matching drops from 1.03 seconds with stock re to 0.06 with re2. (For comparison, a git repo with the same contents and .gitignore file runs "git status -s" in 1.71 seconds, i.e. only slightly faster than hg with re2.)

help: fix extension commands help in keyword search This patch fixes the synopsis shown for extension commands in keyword search results. A previous patch erroneously caused the extension synopsis to be shown instead. Test cases for keyword search are missing, so I added a one.