Python .lower does not seem to properly lowercase all unicode characters (Python 2.7)

I'm trying to normalize latin unicode characters to their lower case forms. I thought I could use the .lower function on a unicode object, but it seems that some parts of unicode are not covered - in particular this block has some characters that do not lowercase: 0xa7a0, 0xa7a2, 0xa7b6, 0xa79e, 0xa79a, 0xa790 all return the same character when .lower is called. I don't anticipate seeing a lot of these characters, so it would be a waste of time to go through all the relevant blocks to fix the ones that don't convert correctly. Is there a more complete function to lowercase unicode, or is this a locale issue?