Fix ZeroDivisionError when ExposureTime contains null values (fix #193)

sigal/image.py

@@ -263,6 +263,8 @@ def get_exif_tags(data):
             except IndexError:
                 # Pillow == 3.0
                 simple['exposure'] = exptime[0]
+            except ZeroDivisionError:
+                logger.info('Invalid ExposureTime: %r', exptime)
         elif isinstance(exptime, int):
             simple['exposure'] = str(exptime)
         else:

tests/test_image.py

@@ -137,6 +137,12 @@ def test_get_exif_tags():
     assert 'gps' not in simple
 
 
+def test_null_exposure_time():
+    data = {'ExposureTime': (0, 0)}
+    simple = get_exif_tags(data)
+    assert 'exposure' not in simple
+
+
 def test_exif_copy(tmpdir):
     "Test if EXIF data can transfered copied to the resized image."