On case-insensitive filesystems it is not such a good idea to have
directories that only differ in case. Packages should be always split
into lowercased directories.
The test data is modified to include some packages starting with
uppercase letters. The example in code can be verified by running
`nosetests --with-doctest`.
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>
