Add missing portage import in portage.locks.
diff --git a/pym/portage/locks.py b/pym/portage/locks.py
index 62380ce..ed20e30 100644
--- a/pym/portage/locks.py
+++ b/pym/portage/locks.py
@@ -12,6 +12,7 @@
 import sys
 import time
 
+import portage
 from portage import os
 from portage.const import PORTAGE_BIN_PATH
 from portage.exception import DirectoryNotFound, FileNotFound, \