the whole test/unittest_compare.py in rql module is marked as broken, find out why

As you can see here:

https://forge.extranet.logilab.fr/open-source/CubicWeb/RQL/blob/c74b5e109a4e785d521af7a9bae4cc674b43624d/test/unittest_compare.py#L40-41

 class RQLCompareClassTest(TestCase):
     """ Compare RQL strings """
     @classmethod
     def setUpClass(cls):
         raise SkipTest('broken')

All those tests are skipped because they are apparently broken.

It might worth it inspecting them and maybe fixing them.