checklink: degrade gracefully on posix when fs is readonly (issue5511) In the unlucky case, checklink tries to make a new file for the symlink test to target. If the filesystem is readonly (perhaps due to permissions in a repo owned by someone else) we just report the filesystem as not supporting symlinks, since the user probably can't write anyway.

revlog: remove some revlogNG terminology RevlogNG is not such a good name when it is no longer the newest revlog version. Since we'll soon have revlog version 2, let's remove some references to it.

revlog: tweak wording and logic for flags validation First, the logic around the if..elif..elif was subtly wrong and sub-optimal because all branches would be tested as long as the revlog was valid. This patch changes things so it behaves like a switch statement over the revlog version. While I was here, I also tweaked error strings to make them consistent and to read better.

tests: tests for revlog version and flags loading We didn't have explicit test coverage of these branches. Better late than never.

perf: allow to clear the obsstore in 'perfvolatilesets' Loading the obsstore can become a large part of the time necessary to compute the important volatile set. We add a flag purging all known obsstore related data. For example, computing the 'bumped' set currently requires reading the full obsstore, so timing greatly differ with or without that flag: Without: ! bumped ! wall 0.005047 comb 0.000000 user 0.000000 sys 0.000000 (best of 446) With: ! bumped ! wall 0.512367 comb 0.510000 user 0.480000 sys 0.030000 (best of 15)

obsolete: test an important corner case Receiving markers affecting changeset we'll receives later is legitimate and not so uncommon case. Working on cache highlighted that this was only testing in the evolve extension. We add a test for this case in core.

largefiles: replace always() method, not _always field We will soon have matchers that don't have an _always field, so largefiles needs to stop assuming that they do. _always is only used by always(), so we safely replace that method instead.

merge with stable

cext: mark constant variables

cext: move util.h to cext tree Since util.h isn't useful in plain C module, it should be placed in CPython extension directory.