Stop storing modulemd without arch

Historically each variant had a list of modules. This is no longer
needed and can be dropped. We can also stop logging the modulemd since
we know it was retrieved from Koji and not modified locally.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/helpers.py

@@ -60,7 +60,6 @@ class MockVariant(mock.Mock):
     def __init__(self, is_empty=False, name=None, *args, **kwargs):
         super(MockVariant, self).__init__(*args, is_empty=is_empty, **kwargs)
         self.parent = kwargs.get('parent', None)
-        self.mmds = []
         self.arch_mmds = {}
         self.module_uid_to_koji_tag = {}
         self.variants = {}
@@ -114,7 +113,6 @@ class MockVariant(mock.Mock):
         if self.modules is None:
             self.modules = []
         self.modules.append(":".join([name, stream, version]))
-        self.mmds.append(mmd)
         if mmd_arch:
             self.arch_mmds.setdefault(mmd_arch, {})[mmd.dup_nsvc()] = mmd
         return mmd