Only permit ascii characters in filenames generated from course_ids.

lms/djangoapps/courseware/management/commands/export_course.py

@@ -83,10 +83,11 @@ def export_course_to_directory(course_key, root_dir):
         raise CommandError("Invalid course_id")
 
     # The safest characters are A-Z, a-z, 0-9, <underscore>, <period> and <hyphen>.
-    # We represent the first four with \w, but generalize to all unicode alphanumerics.
+    # We represent the first four with \w.  
+    # TODO: Once we support courses with unicode characters, we will need to revisit this.
     replacement_char = u'-'
     course_dir = replacement_char.join([course.id.org, course.id.course, course.id.run])
-    course_dir = re.sub(r'[^\w\.\-]', replacement_char, course_dir, flags=re.UNICODE)
+    course_dir = re.sub(r'[^\w\.\-]', replacement_char, course_dir)
 
     export_to_xml(store, None, course.id, root_dir, course_dir)