fixes

rowers/session_utils.py

@@ -10,7 +10,11 @@ def timefield_to_seconds_duration(t):
 
     return duration
 
-
+def timefield_to_minutes_duration(t):
+    duration = t.hour*60.
+    duration += t.minute
+        
+    return duration
 
 def is_session_complete_ws(ws, ps):
     ws = ws.order_by("date")