Fix restart after adding new deps to spawned task.

cylc/flow/data_store_mgr.py

@@ -1194,7 +1194,12 @@ def apply_task_proxy_db_history(self):
                     self.db_load_task_proxies[ikey][0].state.prerequisites
             ):
                 for key in itask_prereq.satisfied.keys():
-                    itask_prereq.satisfied[key] = prereqs[key]
+                    try:
+                        itask_prereq.satisfied[key] = prereqs[key]
+                    except KeyError:
+                        # This prereq is not in the DB: new dependencies
+			# added to an already-spawned task before restart.
+                        itask_prereq.satisfied[key] = False
 
         # Extract info from itasks to data-store.
         for task_info in self.db_load_task_proxies.values():

cylc/flow/task_pool.py

@@ -500,12 +500,19 @@ def load_db_task_pool_for_restart(self, row_idx, row):
                         flow_nums,
                     )
             ):
-                key = (prereq_cycle, prereq_name, prereq_output)
-                sat[key] = satisfied if satisfied != '0' else False
+                # Prereq satisfaction as recorded in the DB.
+                sat[
+                    (prereq_cycle, prereq_name, prereq_output)
+                ] = satisfied if satisfied != '0' else False
 
             for itask_prereq in itask.state.prerequisites:
-                for key, _ in itask_prereq.satisfied.items():
-                    itask_prereq.satisfied[key] = sat[key]
+                for key in itask_prereq.satisfied.keys():
+                    try:
+                        itask_prereq.satisfied[key] = sat[key]
+                    except KeyError:
+			# This prereq is not in the DB: new dependencies
+			# added to an already-spawned task before restart.
+                        itask_prereq.satisfied[key] = False
 
             if itask.state_reset(status, is_runahead=True):
                 self.data_store_mgr.delta_task_runahead(itask)