Reword UserWarning for insecure extraction path so that the message can be...

Reword UserWarning for insecure extraction path so that the message can be keyed for ignoring it. Ref #1899.

pkg_resources/__init__.py

@@ -1235,12 +1235,13 @@ class ResourceManager:
         mode = os.stat(path).st_mode
         if mode & stat.S_IWOTH or mode & stat.S_IWGRP:
             msg = (
-                "%s is writable by group/others and vulnerable to attack "
-                "when "
-                "used with get_resource_filename. Consider a more secure "
+                "Extraction path is writable by group/others "
+                "and vulnerable to attack when "
+                "used with get_resource_filename ({path}). "
+                "Consider a more secure "
                 "location (set with .set_extraction_path or the "
-                "PYTHON_EGG_CACHE environment variable)." % path
-            )
+                "PYTHON_EGG_CACHE environment variable)."
+            ).format(**locals())
             warnings.warn(msg, UserWarning)
 
     def postprocess(self, tempname, filename):