When serving FTP with --auth-proxy, the obscured password was cached in a
driver-global map keyed only by the username. Two sessions that logged in
with the same username but different credentials shared one map entry, so a
later login overwrote it and every subsequent operation on the earlier,
still-authenticated session was re-authorized with the later session's
credential and executed against the later session's backend.
Bind the credential to the FTP session by storing the obscured password in
the per-session goftp Session.Data map instead, so each session always
resolves the backend it authenticated for.
Nick Craig-Wood
f6c81d7a4f