Merge pull request #1399 from docker/1395-docker-py-conflict

Prevent issues when installing docker and docker-py in the same environment

setup.py

@@ -1,10 +1,20 @@
 #!/usr/bin/env python
+from __future__ import print_function
+
 import codecs
 import os
 import sys
 
+import pip
+
 from setuptools import setup, find_packages
 
+if 'docker-py' in [x.project_name for x in pip.get_installed_distributions()]:
+    print(
+        'ERROR: "docker-py" needs to be uninstalled before installing this'
+        ' package:\npip uninstall docker-py', file=sys.stderr
+    )
+    sys.exit(1)
 
 ROOT_DIR = os.path.dirname(__file__)
 SOURCE_DIR = os.path.join(ROOT_DIR)