be sure to first import 'extra' course content from base folder as well as a…

be sure to first import 'extra' course content from base folder as well as a special override folder for the course run

common/lib/xmodule/xmodule/modulestore/xml.py

@@ -444,14 +444,20 @@ class XMLModuleStore(ModuleStoreBase):
             log.debug('========> Done with course import from {0}'.format(course_dir))
             return course_descriptor
 
+
     def load_extra_content(self, system, course_descriptor, category, base_dir, course_dir, url_name):
-        if url_name:
-            path =  base_dir / url_name
 
-        if not os.path.exists(path):
-            path = base_dir
+        self._load_extra_content(system, course_descriptor, category, base_dir, course_dir)
+
+         # then look in a override folder based on the course run
+        if os.path.isdir(base_dir / url_name):
+            self._load_extra_content(system, course_descriptor, category, base_dir / url_name, course_dir)       
+
+
+    def _load_extra_content(self, system, course_descriptor, category, path, course_dir):
 
         for filepath in glob.glob(path/ '*'):
+            if not os.path.isdir(filepath):
                 with open(filepath) as f:
                     try:
                         html = f.read().decode('utf-8')