emitrevision: if we need to compute a delta on the fly, try p1 or p2 first Falling back to `prev` does not yield any real value on modern storage and result in pathological changes to be created on the other side. Doing a delta against a parent will likely be smaller (helping the network) and will be safer to apply on the client (helping future pulls by Triggering intermediate snapshop where they will be needed by later deltas).

emitrevision: simplify the fallback to computed delta Not using the stored delta, or having a full snapshot on disk behave the same ways, so lets use the same code path for that, this is simpler, and it update will be simpler.

emitrevision: also check the parents in the availability closure One of the point of having a closure is to gather the logic in it. So we gather the logic. The `parents[:]` part is a bit ugly but will be replaced by better code soon anyway.

emitrevision: add a small closure to check if a base is usable We will make more use of this and make it more complex too.

chg: scale the timeout in test with the rest This should avoid some flakiness where the logs reports server shutting down.

hghave: we might need py310 and py311 at some point Some tests are already showing slightly different results on Python 3.11. The better idea would be to make them more portable, but if that's not possible, now we can use hghave detection for certain lines. I wonder if there will ever be Python 31.0 and 31.1 though.

hghave: detect Python 3.10 and 3.11 as well Noticed because test-contrib-relnotes.t was skipped.

extensions: load help from hgext.__index__ as a fallback this time Prior to 843418dc0b1b, `hgext.__index__` was consulted first if present, which caused the longer help from the extension modules to be ignored, even when available. But that change causes a bunch of test failures when the pyoxidized binary bundles *.pyc in the binary, saying the there's no help topic for `hg help $disabled_extension` and suggesting the use of `--keyword`, rather than showing a summary and indicating that it is disabled. Current failures were in test-check-help.t, test-extension.t, test-help.t, and test-qrecord.t. Ideally, we would read the various *.pyc files from memory and slurp in the docstring, but I know that they used to not be readable as resources, and I can't figure out how to make it work now. So maybe 3.9 and/or the current PyOxidizer doesn't support it yet. I got closer in py2exe with `importlib.resources.open_binary("hgext", "rebase.pyc")`, but `open_binary()` on *.pyc fails in pyoxidizer.[1] Either way, the *.pyc can't be passed to `ast.parse()` as `extensions._disabledcmdtable()` is doing, so I'm setting that aside for now. [1] https://github.com/indygreg/PyOxidizer/issues/649