Resolving `--account @handle` called `remember` with a `?`, which always re-stamped `handle_checked_at` and so always took the process-global lock, and turned a lock lost to an unrelated process into the command's own failure. `refresh_cached_handle` skips the write while the registry already agrees and the stamp is under a day old, and skips it rather than failing when the lock is busy; `auth status`, which did the same thing once per account, uses it too. Change-Id: I54b1ad5755f4fc903cf49498dce98f4135376c2e