So it appears that the tests in this module expect a predictable element attribute order, which is only added since lxml v3.0alpha1. For example CentOS-6 natively ships with lxml v2.2.3.
For the effort of upstreaming this module, we opted to filter out these tests when the lxml version is not greater or equal to 3. The module still works fine, we simply are not comparing as smart as we should.