libmat2: images: fix handling of .JPG files

Pixbuf only supports .jpeg files, not .jpg, so libmat2 looks for such an
extension and converts it if necessary. As this check is case sensitive,
processing .JPG files does not work.

Fixes #47.

Signed-off-by: Antoine Tenart <antoine.tenart@ack.tf>

libmat2/images.py

@@ -82,7 +82,7 @@ class GdkPixbufAbstractParser(_ImageParser):
     def remove_all(self):
         _, extension = os.path.splitext(self.filename)
         pixbuf = GdkPixbuf.Pixbuf.new_from_file(self.filename)
-        if extension == '.jpg':
+        if extension.lower() == '.jpg':
             extension = '.jpeg'  # gdk is picky
         pixbuf.savev(self.output_filename, extension[1:], [], [])
         return True