Revert "Expand variables in configuration files" - I feel I've been here before.

Breaks some test runs.

This reverts commit a9eef029.

lib/ansible/constants.py

@@ -79,7 +79,7 @@ def shell_expand_path(path):
     ''' shell_expand_path is needed as os.path.expanduser does not work
         when path is None, which is the default for ANSIBLE_PRIVATE_KEY_FILE '''
     if path:
-        path = os.path.expandvars(os.path.expanduser(path))
+        path = os.path.expanduser(path)
     return path
 
 p = load_config_file()