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.
Added signature for changeset
bb42988c7e15
Added tag 6.5rc0 for changeset
bb42988c7e15