Merge "Fix release note theme for virtualbmc"

releasenotes/source/conf.py

@@ -43,10 +43,15 @@
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
 extensions = [
-    'openstackdocstheme',
     'reno.sphinxext'
 ]
 
+try:
+    import openstackdocstheme
+    extensions.append('openstackdocstheme')
+except ImportError:
+    openstackdocstheme = None
+
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']
 
@@ -97,7 +102,10 @@ todo_include_todos = False
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 #
-html_theme = 'alabaster'
+if openstackdocstheme is not None:
+    html_theme = 'openstackdocs'
+else:
+    html_theme = 'default'
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the