obshistory: use effect flags from obsutil They were added there in 51aadc0d0da2::187bc224554a (hg 4.4).

obshistory: make a {flag value: description} dict for _markerseffects()

obshistory: factor out _markerseffects()

obshistory: factor out _markerspreciseverb()

evolve: provide branch argument to overlayworkingctx.tomemctx() This is related to upstream 2ecbc4ec87d8 and fixes test-evolve.t.

changelog: mention all the cleanups as one item

templatekw: drop obsfatedata and related code AFAIU, this function exists so that people could hack together a replacement template for {obsfate} if they weren't satisfied with the default, but only on older versions. It seems that 3d0f8918351b::d0f1e3d3ef4d was the series introducing obsfate* functions that can show specific obsmarker properties, and that was included in hg 4.4. obsfatedata was already claimed to be removed in 35ffd7a4b339 and then more of its usage was removed in 9882fed37ea9. There are no users in evolve and in core hg, no tests and nothing else mentions obsfatedata.

templatekw: drop obsfateprinter() and obsfatelineprinter() They were unused (probably because their versions were already pushed to hg 4.4).

compat: drop isobsnotesupported() that checks if storing notes is supported The check is identical to checking if core has e27f1f04c2cf (hg 4.4).

templatekw: use literal set syntax According to https://www.mercurial-scm.org/wiki/SupportedPythonVersions, we don't support Python 2.6 since 4.3.