[1.5.x] Fixed #18985 -- ensure module level deprecations are displayed

Also don't compete with -W CLI option.

Thanks to Aymeric Augustin for the catch, and Claude Paroz for the patch.

Backport of e79b857a07 from master.

tests/runtests.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python
+import logging
 import os
 import shutil
 import subprocess
@@ -106,6 +107,14 @@ def setup(verbosity, test_labels):
     # in our tests.
     settings.MANAGERS = ("admin@djangoproject.com",)
 
+    if verbosity > 0:
+        # Ensure any warnings captured to logging are piped through a verbose
+        # logging handler.  If any -W options were passed explicitly on command
+        # line, warnings are not captured, and this has no effect.
+        logger = logging.getLogger('py.warnings')
+        handler = logging.StreamHandler()
+        logger.addHandler(handler)
+
     # Load all the ALWAYS_INSTALLED_APPS.
     # (This import statement is intentionally delayed until after we
     # access settings because of the USE_I18N dependency.)