devstack master is rocky now

See #snowpenstack!

Change-Id: I2df485c2acf1bec0d0f7ddc6538bff2c2ec141e3
diff --git a/stackrc b/stackrc
index aebf152..4f627cc 100644
--- a/stackrc
+++ b/stackrc
@@ -258,7 +258,7 @@
 # Setting the variable to 'ALL' will activate the download for all
 # libraries.
 
-DEVSTACK_SERIES="queens"
+DEVSTACK_SERIES="rocky"
 
 ##############
 #