Fix SWIFT_HASH_PREFIX variable.
diff --git a/stack.sh b/stack.sh
index 83fec6a..7f2a5a2 100755
--- a/stack.sh
+++ b/stack.sh
@@ -655,7 +655,7 @@
 
    # Generate swift.conf, we need to have the swift-hash being random
    # and unique.
-   sed -e "s/%SWIFT_HASH%/$swift_hash/" $FILES/swift.conf > /etc/swift/swift.conf
+   sed -e "s/%SWIFT_HASH%/$SWIFT_HASH/" $FILES/swift.conf > /etc/swift/swift.conf
 
    # We need to generate a object/account/proxy configuration
    # emulating 4 nodes on different ports we have a litle function