dirstate-v2: actually fix the dirstate-v2 upgrade race...
dirstate-v2: actually fix the dirstate-v2 upgrade race
It looks like the previous fix for the dirstate-v2 upgrade race didn't work.
The problem is that it only recovers in case the size of the v1 `dirstate` file
is smaller than the `v2` one, whereas in real life it's always larger.
This commit changes the test to be more realistic, which reveals the crash,
and changes the code to fix the crash.