dirstate: deal with read-race for pure python code If we cannot read the dirstate data, this is probably because a writing process wrote it under our feet. So refresh the docket and try again a handful of time.

dirstate: abstract the reading of the data file in v2 in a method We will need more changes to avoid some race conditions during read, so we first isolate the simple logic before making it more complicated.

dirstate: add append/new-file variants in the dirstate's read race tests This covers more ground and finds more bugs. At that point I gave up on making things as `known-bad-output` / `missing-correct-output` as this gets too messy.

dirstate: add a synchronisation point in the middle of the read This will be useful to test some more race conditions around dirstate.

dirstate: add v1-v2 variants to the dirstate's read race tests More cases mean different issues.

dirstate: check dirstate race condition around status More problems to solve.

dirstate: check dirstate race condition around update More problems to solve.

dirstate: check dirstate race condition around commit Once in a while, rhg is the only one to behave right here.

dirstate: initial creation of a test file to check dirstate race read More problems to solve… yeah ! (I guess)

dirstate: add a synchronisation point before doing a full dirstate read This will be useful to test some race conditions around the dirstate.