dirstate-v2: complain early on docket name collision The alternative is that the dirstate gets deleted so the corruption persists and is hard to investigate. This happened to me in tests, where the dirstate names are taken from file, since the file got reverted. I expect this can also happen in prod with non-trivial probability (1/4 billion).

setup: further improve the error path for version retrieval This is a new take at the problem that 8d390a13474d tried to tackle. There was two issues after that previous improvement: - the 0.0+ version could survive a bit too long and reaching the installer version and staying there. - multiple use case where still failing. So the new code is better at: - always succeeding when running `make local` so that we can bootstrap a local version - no using that fallback outside of `make local` to avoid distribution of version with the buggy version number. The setup.py is a gigantic pile of spaghetti code, to the point where pastafarian pilgrim started knocking at its core. However I refrained from cleaning that up since the more to a `setup.cfg` means this code should be deleted soon™.

dirstate: handle missing backup file on restoration This is the stable counter part to e358f6e0e50e. Since 6.4 will stop writing undo.dirstate in some case (actually… at all), a transaction created with 6.4 and recover/rolledback with 6.3 need to work to a certain degreee. This changeset add the necessary bits so that we don't get a traceback from 6..3 in this cases.

tag: disallow tagging the working directory It's kinda silly, but a clear error message is better than a stacktrace about subscripting `None` when trying to generate the default commit message. I'm surprised that `.revsingle(..).node()` returns None instead of `nodemod.wdirid`, but now there's a test to catch if this changes.

test: fix the flakyness in test-remotefilelog-local.t I now get about 80% of my `test-chg` CI run that fails on flakyness in this tests. It turns out this is only ambiguous status that end up doing file download. So… calling status early will do that potential download separately and the calls we scrutinize during that test will be just fine.

fix: add more information to the debug output The previous debug output did not help to understand which file where fixed in which revision. The new output should cover that.