bookmark: improve ambiguous documentation for rename

ui: change default path fallback mechanism (issue4796) The previous paths API code always fell back to the default path. This was wrong because if a requested path doesn't exist, that should error. Only if no path was requested should we fall back to the default. As part of implementing the test case for issue 4796, it was discovered that the "repository does not exist" error message raised by localrepository.__init__ wasn't being seen because the paths API validates paths before localrepository.__init__ was being called. The exception and error message from localrepository.__init__ has been introduced to getpath(). This necessitated rewriting expandpath() both to catch the exception and to have proper default fallback. This code is more complicated than I'd like. But making all tests pass was a big chore. As more code moves to getpath(), there will likely be opportunities to improve things a bit.

templater: catch regexp error at sub() function This patch splits re.sub() into re.compile() and sub() so that it can distinguish which argument causes re.error.

graphmod: compute slow revset query once prior to reachableroots (issue4782) Because revsets query is evaluated lazily, "list(revs)" may take long for complicated query. So we shouldn't iterate revs many times. This patch is the easiest workaround for the issue4782. We could introduce more aggressive caching, but it wouldn't be as fast as the simple baseset operation. Gregory Szorc said "this makes `hg wip` on my Firefox clone ~4x faster than 3.5.1 (~6.5s to ~1.5s). This is after a regression in @ to ~45s."

profiling: add config option for enabling profiling Previously you could only enable profiling via the --profile option. This is awkward when trying to debug a server side operation. Let's add a config option to enable profiling. In the future, this could be extended to allow profiling a certain percentage of operations (and potentially reporting that information to an external service).

blackbox: add pid to output This adds the process id to the line header for the blackbox output. This is useful for distinguishing processes when using the blackbox on a server and many processes are writing to the blackbox at once.

exchange: allow fallbackheads to use lazy set behavior The common ancestor set implementation was made lazy a couple years ago, but this piece of code still required processing the entire repo by putting set() around the lazy set. The code was introduced in 5653f2d166ea, a year before the lazy ancestor set was added. Dropping the set() shaves 3.5 seconds off of 'push -r' in repos with hundreds of thousands of commits.

hgweb: move templater instantiation to requestcontext This code needs to access a lot of config options. All our config lookups have moved to requestcontext. It makes sense to move this function there.

help/config: make defaults consistent

help/config: reword allow_push to fix grammar