Fix get_func bug.

cylc/flow/config.py

@@ -1795,6 +1795,7 @@ def generate_triggers(self, lexpression, left_nodes, right, seq,
                 )
 
             if self.xtrigger_mgr is None:
+                # Validation only.
                 XtriggerManager.validate_xtrigger(label, xtrig, self.fdir)
             else:
                 self.xtrigger_mgr.add_trig(label, xtrig, self.fdir)

cylc/flow/subprocpool.py

@@ -79,9 +79,9 @@ def get_func(mod_name, func_name, src_dir):
         AttributeError, if the function is not found in the module
 
     """
-    if func_name in _XTRIG_FUNCS:
+    if (mod_name, func_name) in _XTRIG_FUNCS:
         # Found and cached already.
-        return _XTRIG_FUNCS[func_name]
+        return _XTRIG_FUNCS[(mod_name, func_name)]
 
     # 1. look in <src-dir>/lib/python.
     sys.path.insert(0, os.path.join(src_dir, 'lib', 'python'))
@@ -94,8 +94,8 @@ def get_func(mod_name, func_name, src_dir):
 
     # Module found and imported, return the named function.
 
-    _XTRIG_FUNCS[func_name] = getattr(mod_by_name, func_name)
-    return _XTRIG_FUNCS[func_name]
+    _XTRIG_FUNCS[(mod_name, func_name)] = getattr(mod_by_name, func_name)
+    return _XTRIG_FUNCS[(mod_name, func_name)]
 
 
 def run_function(func_name, json_args, json_kwargs, src_dir):

cylc/flow/xtriggers/wall_clock.py

@@ -38,12 +38,11 @@ def validate_config(f_args, f_kwargs, f_signature):
     wall_clock(PT1H)
     wall_clock(offset=PT1H)
 
-    And offset must be a valid ISO 8601 interval.
+    The offset must be a valid ISO 8601 interval.
 
     If f_args used, convert to f_kwargs for clarity.
 
     """
-
     n_args = len(f_args)
     n_kwargs = len(f_kwargs)