qdict_array_split() should terminate if it encounters both an entry with
a key of "%u" and entries with keys prefixed "%u." for the same index.

This patch adds a test for this case.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>