
Since [1], the IPRoute API methods are dynamic loaded attributes,
defined in the ``RTNL_API`` mixin class. In order to mock them,
it is needed to use the argument ``create=True``.
This code is compatible with older and newer versions of pyroute2.
[1]d45678c7c9 (diff-31320c43ab56dfae39c507c540d7c22a5c9ecb42490c2d739ed97c25967e61a8)
Closes-Bug: #2106605
Change-Id: I3b4b103912f5c2e3fe5a0312367f5675ebbba68f