Detect conflicting version of the docker python SDK and prevent execution until issue is fixed

Signed-off-by: Joffrey F <joffrey@docker.com>

compose/cli/main.py

@@ -14,6 +14,30 @@ from distutils.spawn import find_executable
 from inspect import getdoc
 from operator import attrgetter
 
+
+# Attempt to detect https://github.com/docker/compose/issues/4344
+try:
+    # A regular import statement causes PyInstaller to freak out while
+    # trying to load pip. This way it is simply ignored.
+    pip = __import__('pip')
+    pip_packages = pip.get_installed_distributions()
+    if 'docker-py' in [pkg.project_name for pkg in pip_packages]:
+        from .colors import red
+        print(
+            red('ERROR:'),
+            "Dependency conflict: an older version of the 'docker-py' package "
+            "is polluting the namespace. "
+            "Run the following command to remedy the issue:\n"
+            "pip uninstall docker docker-py; pip install docker",
+            file=sys.stderr
+        )
+        sys.exit(1)
+except ImportError:
+    # pip is not available, which indicates it's probably the binary
+    # distribution of Compose which is not affected
+    pass
+
+
 from . import errors
 from . import signals
 from .. import __version__