Replace functools.wraps with six.wraps

Previously we have been using functools.wraps. However if any decorator
that uses functools.wraps is used, some code that relies on __wrapped__
being present, e.g. pytest, will fail on Python2. Switching to six.wraps
will solve this problem, as it introduces this change as well and solves
the missing __wrapped__ attribute.

Signed-off-by: Vinzenz Feenstra <vfeenstr@redhat.com>

leapp/utils/clicmd.py

@@ -1,9 +1,10 @@
-import functools
 import os
 import sys
 
 from argparse import ArgumentParser, _SubParsersAction, RawDescriptionHelpFormatter
 
+import six
+
 from leapp.exceptions import CommandDefinitionError, UsageError, CommandError
 
 
@@ -277,7 +278,7 @@ def wrapper(f):
 
 
 def _ensure_command(wrapped):
-    @functools.wraps(wrapped)
+    @six.wraps(wrapped)
     def wrapper(f):
         if not hasattr(f, 'command'):
             f.command = Command('')

leapp/utils/deprecation.py

@@ -1,9 +1,10 @@
 import datetime
-import functools
 import inspect
 import warnings
 from collections import namedtuple
 
+import six
+
 from leapp.models import Model
 
 
@@ -31,7 +32,7 @@ def decorator(item):
                     ' Use the decorator on the affected methods instead of the current class.'
                 )
 
-        @functools.wraps(target_item)
+        @six.wraps(target_item)
         def process_wrapper(*args, **kwargs):
             # we need to remove later just items that we add right now
             # added_items == new items we add now to ...
@@ -106,14 +107,14 @@ def do_warn():
         if inspect.isclass(item):
             old_init = item.__init__
 
-            @functools.wraps(item.__init__, assigned=('__name__', '__doc__'))
+            @six.wraps(item.__init__, assigned=('__name__', '__doc__'))
             def wrapper(*args, **kwargs):
                 do_warn()
                 return old_init(*args, **kwargs)
             item.__init__ = wrapper
             result = item
         else:
-            @functools.wraps(item)
+            @six.wraps(item)
             def wrapper(*args, **kwargs):
                 do_warn()
                 return item(*args, **kwargs)