refactor mirror safing code

scene_checks.py

@@ -24,7 +24,7 @@ def safing_check(frame, parameters):
     if not np.in1d(['hatchOpen','sceneMirrorPosition'], frame.columns).all():
         return frame
 
-    hatch_closing = ((frame.hatchOpen == 1)  & ((frame.hatchOpen == -3).diff(-1) == 1)).shift(1)
+    hatch_closing = (frame.hatchOpen == 1).shift(1)  & (frame.hatchOpen == -3)
     mirror_safing = (hatch_closing & frame.sceneMirrorPosition.isin([ord('H'), ord('A')]))
     frame['safing_check'] = mirror_safing * 1
     annotate_all(frame, mirror_safing, 'mirror likely safed during view')