Work around pypy testing issue

A recent release of setuptools appears to have introduced a bug that
causes the pypy gate tests to fail.  This applies a temporary workaround
that should restore pypy testing while the root cause of the problem is
researched.

Change-Id: I66597e40c1d2e57cca1292844d228af85214197d
Partial-Bug: 1290562

tox.ini

@@ -12,6 +12,11 @@ deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands = python setup.py testr --testr-args='{posargs}'
 
+[testenv:pypy]
+deps = setuptools<3.2
+       -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
+
 [testenv:pep8]
 commands = flake8