dirstate: set identity whenever we read the dirstate's v2 docket The docket can be loaded outside of a full read (for exemple when pre-fetching parents), so the current code would read/set the identity after loading the data, opening a race condition: A0: first process docket is read B0: other process appends new data to the dirstate (and changes the docket) A1: first process sets the identity (based on pre-B content, but with post-B identity) A1: first process loads the dirstatemap from the data file A1: first process does not detect the race and overwrites the update from B.