Fix dogpile.cache 0.7.0 interaction

Due to the change in behavior in dogpile.cache > 0.7.0 where bound
methods can no longer be passed to the cache_on_arguments decorator,
openstackSDK now explicitly provides a non-method wrapper for all
elements passed to cache_on_arguments. This is handled via an explicit
no-op decorator. functools.wraps is used to preserve data from the
original method.

Needed-By: https://review.openstack.org/#/c/624993
Change-Id: Ied27fa1e834d145246815afcb67c59d48669ffb2
Story: 2004605
Task: 28502

shade/_utils.py

@@ -14,6 +14,7 @@
 
 import contextlib
 import fnmatch
+import functools
 import inspect
 import jmespath
 import munch
@@ -414,6 +415,18 @@ def valid_kwargs(*valid_args):
     return func_wrapper
 
 
+def _func_wrap(f):
+    # NOTE(morgan): This extra wrapper is intended to eliminate ever
+    # passing a bound method to dogpile.cache's cache_on_arguments. In
+    # 0.7.0 and later it is impossible to pass bound methods to the
+    # decorator. This was introduced when utilizing the decorate module in
+    # lieu of a direct wrap implementation.
+    @functools.wraps(f)
+    def inner(*args, **kwargs):
+        return f(*args, **kwargs)
+    return inner
+
+
 def cache_on_arguments(*cache_on_args, **cache_on_kwargs):
     _cache_name = cache_on_kwargs.pop('resource', None)
 
@@ -421,7 +434,7 @@ def cache_on_arguments(*cache_on_args, **cache_on_kwargs):
         def _cache_decorator(obj, *args, **kwargs):
             the_method = obj._get_cache(_cache_name).cache_on_arguments(
                 *cache_on_args, **cache_on_kwargs)(
-                    func.__get__(obj, type(obj)))
+                    _func_wrap(func.__get__(obj, type(obj))))
             return the_method(*args, **kwargs)
 
         def invalidate(obj, *args, **kwargs):