tests: show failure to `hg add -I` a dir->symlink transition

setup: try a non-pure version of the local Mercurial if the pure fails Things like `zstd` can make the pure version fails.

setup: make debug simpler by adding a `__repr__` to `hgcommand` This help when trying to debug this logic.

censor: fix things around inlining The temporary revlog cannot go through the inline → split process as this would break at transaction commit. (that might be fixable, but lets keep things simple for now). We introduce a cleaner way to enforce this as the previous one was broken in 6.6 On the way we remove multiple weird, fragile and broken overwrite of revlog attributes and we focus on passing the configuration across. We also had to update the test to actually create a non-inline revlog.

revlog: add a `may_inline` argument to revlog This allow for a clean skipping of the inline feature when needed, for example by censor.

revlog: allow explicit passing of config to revlog This will be useful to fix censor in a later changeset.

censor: show that the `not-inline` → `inline` test is broken The source revlog should not be inlined and it is…

rhg: support rhg status --rev --rev

rust: add a utility function to merge ordered fallible iterators Adding a function merge_join_results_by, a version of itertools::merge_join_by that works on "fallible" iterators (iterators that can produce errors)

rhg: refactor hg status, make the display code usable for non-dirstate status