Don't try to run issubclass on non-classes2.14.0

issubclass gets cranky if you give it a first argument that is not a
class.

  http://logs.openstack.org/74/612474/2/check/cross-osc-build-sphinx-docs/42250a7/job-output.txt.gz#_2018-10-26_08_02_08_597700

Shows a failure when trying to build python-openstackclient docs with
the cliff sphinxext after updating openstacksdk in such a way that an
import error went away.

Change-Id: Id1d17c66e5dd6e430376a8d6ea74abc4da5cbc75

1 files changed, 3 insertions, 0 deletions

diff --git a/cliff/sphinxext.py b/cliff/sphinxext.py
index 5ec3448..8a9a2e6 100644
--- a/cliff/sphinxext.py
+++ b/cliff/sphinxext.py
@@ -15,6 +15,7 @@
 import argparse
 import fnmatch
 import importlib
+import inspect
 import re
 import sys
 
@@ -242,6 +243,8 @@ class AutoprogramCliffDirective(rst.Directive):
             cliff_app_class = getattr(sys.modules[mod_str], class_str)
         except AttributeError:
             return
+        if not inspect.isclass(cliff_app_class):
+            return
         if not issubclass(cliff_app_class, app.App):
             return
         app_arguments = self.options.get('arguments', '').split()