JpegImagePlugin._getexif expects no exif key in info dict, not None
Merge branch 'fix-typeerror' of https://github.com/homm/Pillow into webp_exif
Test for PR#498
Merge pull request #499 from wiredfool/webp_exif

*  Don't send None as exif to JpegImagePlugin._getexif -- homm 
*  Test for fix -- wiredfool