title: IOError: cannot identify image file
body: <p>Can anyone tell why PIL can't open this PNG file?</p>
  
  <p><a href="https://b75094855c6274df1cf8559f089f485661ae1156.googledrive.com/host/0B56ak7W-HmqAX005c3g5eTlBakE/8.png" rel="nofollow">https://b75094855c6274df1cf8559f089f485661ae1156.googledrive.com/host/0B56ak7W-HmqAX005c3g5eTlBakE/8.png</a></p>
  
  <p>I get IOError: cannot identify image file, and by looking at the code, it seems it tries PIL.PngImagePlugin.PngImageFile and corresponding "accept" function, and it returns False</p>
  
  <p>I'm using version 1.1.6</p>