remote/coordinator: report expired lease extension

Reject lease extension requests with a specific expired-reservation error when
the reservation timeout has already passed.

This avoids returning the generic "not in leased state" error before the
scheduler has processed the expired reservation.

Author: idan-arm

labgrid/remote/coordinator.py

@@ -1516,6 +1516,12 @@ async def ExtendLease(self, request, context, *, identity):
                 f"Reservation {token} is owned by a different user",
             )
 
+        if reservation.expired:
+            await context.abort(
+                grpc.StatusCode.FAILED_PRECONDITION,
+                f"Reservation {token} has expired",
+            )
+
         if reservation.state is not ReservationState.leased:
             await context.abort(
                 grpc.StatusCode.FAILED_PRECONDITION,