typing: suppress a bunch of potential import-error cases in extensions As flagged by pytype locally. Either the ImportError is locally handled, or the imported module was previously determined to be present by `hgave` (for the phabricator extension), or is handled by the `hgext.convert.subversion` module when imported (for the `hgext.convert.transport` module).

watchman: drop some py2 compat code The `unicode` reference was being flagged by pytype, even though it was never evaluated on py3. There's more that can be dropped and `compat.py` can probably be inlined if we don't care about minimizing the code changes from FB. But I don't feel like dealing with that.

pytype: add coverage for hgdemandimport This would have flagged what needed fixing in 48e38b179106 long ago.

hgweb: skip body creation of HEAD for most requests The body is thrown away anyway, so this just wastes a lot of CPU time. In the case of /archive/, this skips manifest processing and the actual file archiving, resulting in a huge difference. The most tricky part here is skipping the Content-Length creation as it would indicate the output size for the corresponding GET request.

branching: merge stable into default

urlutil: drop the deprecated `getpath()` This was deprecated in 5.9.

ui: drop the deprecated `getpath()` This was deprecated in 5.9.

ui: drop the deprecated `expandpath()` This was deprecated since 5.8.

relnotes: last-minute addition to 6.3.2

relnotes: add 6.3.2