packaging: prepare release 6.3.0

test-compat: merge with mercurial-3.9

test-compat: merge with mercurial-4.0 branch The new 'olog' command is not working with 3.9 so we skill all mentions of it in the tests. This also apply to the topic extensions.

test-compat: merge with mercurial-4.1 hg log has no trouble field in mercurial 4.0, output fixed.

test-compat: merge with stable Nothing special to report, minor test-metaedit.t output change.

merge with default

compat: fix stablerange for mercurial 3.9 Lrudict.get change of api between mercurial 3.9 and mercurial 4.2. Bypass this limitation by using lrudict.__getitem__ and catch the KeyError directly.

template: fix successors and precursors templates In mercurial 4.1-, the gen argument is expected to be an iterator and not an iterable, fix successors and precursors templates.

lint: remove double newline in test file Test file test-stablesort-criss-cross.t contained two double newline, I remove them.

template: fix precursors template for older mercurial version In mercurial 4.1 and below templatekw._hybrid require the gen argument to be different than None. Manually compute the same default output for these older mercurial versions.