Previously every user did login → change-pass → re-login in on_start
regardless of whether the server actually required a password change.
With bcrypt at ~250ms/call that's 3 bcrypt-bound requests per user.
At 2500 users the on_start queue was ~10k bcrypt ops — users never
escaped warmup, so @task endpoints never fired.
Login already returns must_change_password; only run the change-pass
+ re-login dance when the server says we have to. Cuts on_start from
3 requests to 1 for every user after the first DB initialization.
anti
d3f4bbb62b