Upgrading Persistent Storage times out on some systems and displays an error in the Welcome Screen but succeeds in the background

from wb:ffe40d6366e7bcaf76e887756e185151:

Jun 14 15:16:36 amnesia tps[6129]: INFO:service.py:385: Upgrading Persistent Storage...
[...]
Jun 14 15:18:36 amnesia tps[6129]: INFO:service.py:327: Unlocking Persistent Storage...
Jun 14 15:18:36 amnesia tps[6129]: ERROR:object.py:190: [2] Can't unlock when state is 'UPGRADING'
Jun 14 15:18:36 amnesia tps[6129]: Traceback (most recent call last):
Jun 14 15:18:36 amnesia tps[6129]:   File "/usr/lib/python3/dist-packages/tps/dbus/object.py", line 178, in handle_method_call_inner
Jun 14 15:18:36 amnesia tps[6129]:     result = func(*parameters)
Jun 14 15:18:36 amnesia tps[6129]:   File "/usr/lib/python3/dist-packages/tps/service.py", line 332, in Unlock
Jun 14 15:18:36 amnesia tps[6129]:     raise FailedPreconditionError(msg)
Jun 14 15:18:36 amnesia tps[6129]: tps.dbus.errors.FailedPreconditionError: Can't unlock when state is 'UPGRADING'
Jun 14 15:18:36 amnesia tails-greeter.desktop[6107]: [ERROR] persistent_storage.py:97 do_unlock_storage: Error unlocking Persistent Storage: g-io-error-quark: GDBus.Error:org.boum.tails.PersistentStorage.Error.FailedPrecondition: Can't unlock when state is 'UPGRADING' (36)
Jun 14 15:18:55 amnesia tps[6129]: INFO:service.py:401: Done upgrading Persistent Storage