Skip integration tests when one of the packages under test is already...

Skip integration tests when one of the packages under test is already installed, as the installation will fail in that case.

setuptools/tests/test_integration.py

@@ -14,6 +14,17 @@ from setuptools.command import easy_install as easy_install_pkg
 from setuptools.dist import Distribution
 
 
+def setup_module(module):
+    packages = 'stevedore', 'virtualenvwrapper', 'pbr', 'novaclient'
+    for pkg in packages:
+        try:
+            __import__(pkg)
+            tmpl = "Integration tests cannot run when {pkg} is installed"
+            pytest.skip(tmpl.format(**locals()))
+        except ImportError:
+            pass
+
+
 @pytest.fixture
 def install_context(request, tmpdir, monkeypatch):
     """Fixture to set up temporary installation directory.