obsolete: add operation metadata to rebase/amend/histedit obsmarkers By recording what operation created the obsmarker, we can show very intuitive messages to the user in various UIs. For instance, log output could have messages like "Amended as XXX" to show why a commit is old and has an 'x' on it. @ ac28e3 durham / First commit | | o d4afe7 durham | | Second commit | | | x 8e9a5d (Amended as ac28e3) durham |/ First commit |

obsolete: invalidate "volatile" set cache after merging marker Adding markers to the repository might affect the set of obsolete changesets. So we most remove the "volatile" set who rely in that data. We add two missing invalidations after merging markers. This was caught by code change in the evolve extensions tests. This issues highlight that the current way to do things is a bit fragile, however we keep things simple for stable.

match: use match.prefix() in subdirmatcher It seems like the subdirmatcher should be checking if the matcher it's based on is matching prefixes. It was effectively doing that already because "prefix() == not always() and not anypats() and not isexact()", subdirmatcher was checking the first two parts of that condition and I don't think it will ever be given an "exact" matcher with it's directory name (because exact matchers are for matching files, not directories). Still, let's switch to using prefix() for clarity (and because I'm trying to remove code that reaches for matchers internals).