Fix the typo of Q_USE_ROOTWRAP expression.

Fixes bug 1071636

Change-Id: If384d1d9205300e11722e5280107b773368825ba
diff --git a/stack.sh b/stack.sh
index e58c439..80860ab 100755
--- a/stack.sh
+++ b/stack.sh
@@ -338,7 +338,7 @@
 Q_AUTH_STRATEGY=${Q_AUTH_STRATEGY:-keystone}
 # Use namespace or not
 Q_USE_NAMESPACE=${Q_USE_NAMESPACE:-True}
-Q_USE_ROOTWRAP=${Q_USE_ROOTWRAP=:-True}
+Q_USE_ROOTWRAP=${Q_USE_ROOTWRAP:-True}
 # Meta data IP
 Q_META_DATA_IP=${Q_META_DATA_IP:-$HOST_IP}