pager: use less as a fallback on Unix This seems reasonable choice per discussion, and the default-default of Git. See also the inline-comment for why. https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-April/097042.html

test-bookmarks: factor hooks out to a shell script for Windows The previous incarnation of the hooks weren't being run on Windows, which altered the DAG and hashes[1]. [1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-April/096987.html

help: explain how to access subtopics in internals

log: document the characters ---graph uses to draw The meaning of : vs | was undocumented and non-obvious.

tests: demonstrate that pager.attend-<abbreviated> doesn't work A pager.attend-* value that isn't a full command or alias name doesn't work. We add explicit test coverage of this to demonstrate it.

tests: test that abbreviated command alias is also paged Explicit test coverage is good.

tests: drop unnecessary pager attend in test `log` is attended by default. We don't need to specify pager.attend-log in this test.

hgweb: change text of followlines links to "older / newer" DAG directions "descending" / "ascending" arguably do not make much sense in the web interface where changes are usually listed by "dates".

hgweb: do not show "descending" link in followlines UI for filelog heads When on a filelog head, we are certain that there will be no descendant so the target of the "descending" link will lead to an empty log result. Do not display the link in this case.

context: optimize linkrev adjustment in blockancestors() (issue5538) We set parent._descendantrev = child.rev() when walking parents in blockancestors() so that, when linkrev adjustment is perform for these, it starts from a close descendant instead of possibly topmost introrev. (See `self._adjustlinkrev(self._descendantrev)` in filectx._changeid().) This is similar to changeset c82d88dfaf59, which added a "f._changeid" instruction in annotate() for the same purpose. However, here, we set _descendantrev explicitly instead of relying on the '_changeid' cached property being accessed (with effect to set _changeid attribute) so that, in _parentfilectx() (called from parents()), we go through `if '_changeid' in vars(self) [...]` branch in which instruction `fctx._descendantrev = self.rev()` finally appears and does what we want. With this, we can roughly get a 3x speedup (including in example of issue5538 from mozilla-central repository) on usage of followlines revset (and equivalent hgweb request).