Why does test_upload assert type=None?

[cen1]

Since the last issue was reopened I decided to retest my backend and besides the cover thing it passes the tests except this assert: In test_upload, the self.assertEquals(file_data['type'], None) failed for me. My returned value was image/png which should be correct since a png was uploaded. I have a three step mime type finder. First I check via form metadata, then via Apache Tika and finally from file extension. I didn't test the official backend but I checked the network on the Try page and it does return the image type in JSON.

I think it shoud be self.assertEquals(file_data['type'], "image/png")