Updated from global requirements

Change-Id: I54f89ffa49d3fdc8cc71528faef7b10f115370b2
diff --git a/test-requirements.txt b/test-requirements.txt
index d7340f3..3fe2f27 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -2,7 +2,7 @@
 # needed for doc build
 docutils==0.9.1
 sphinx>=1.1.2,<1.2
-python-subunit
+python-subunit>=0.0.18
 oslo.sphinx
 mox>=0.5.3
 mock>=1.0