model_forms tests break on Windows after 
|Reported by:||Gulopine||Owned by:||Gulopine|
|Has patch:||yes||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
in , addition model_forms tests were introduced that opened a PNG in the test suite, but no mode was specified. Then, when  went in, the tests were updated to use ImageField instead of FileField, which runs the content through PIL. This works fine in Unix-like environments, but on Windows, that opens the file in text mode, which only reads for 5 bytes. Then, when run through PIL, it rightfully doesn't recognize it as a valid image.