demandimport: error out early on missing attribute of non package (issue5373) If the parent module isn't a package, all valid attributes must be obtained from it. We can raise ImportError early if any attributes not found.

demandimport: add 'nt' to ignore list (issue5373) pathlib2 tries to import nt. Since it is a built-in module, there should be no performance penalty. https://github.com/mcmtroffaes/pathlib2/blob/release/2.2.0/pathlib2.py#L33

demandimport: add '_ctypes.pointer' to ignore list on PyPy The pointer module is shadowed by a subsequent import. Our demand importer can't handle this because both sub modules and attributes live in the same namespace. https://bitbucket.org/pypy/pypy/src/release-5.0.1/lib_pypy/_ctypes/__init__.py#__init__.py-5

hgweb: make anchor name actually match its href on help index page

perf: add perfchangegroupchangelog command This command can be used for testing the performance of producing the changelog portion of a changegroup. We could use additional perf* commands for testing other parts of changegroup. Those can be written another time, when they are needed. (And those may want to refactor the changegroup generation API so code can be reused.) Speaking of code reuse, yes, this command does reinvent a small wheel. I didn't want to scope bloat to change the changegroup API because that will invite bikeshedding.

perf: add --reverse to perfrevlog It can be useful to know how fast we can read revisions from a revlog in reverse. This operation tends to occur in `hg log` commands, for example.