mkexp: Changed to suppress 'exist' warning if data dir is prefix of script dir

mkexp

@@ -181,7 +181,7 @@ data_dir = config['DATA_DIR']
 print "Data directory: '"+data_dir+"'"
 if not os.path.isdir(data_dir):
     os.makedirs(data_dir)
-else:
+elif not script_dir.startswith(data_dir):
     feedback.warning("data directory already exists")
 
 # Create directory for running the experiment if it doesn't exist