Match device pattern on start of line in MastershipStore election topics

Change-Id: I2ee7c3596b90d7096ae456269e37f18970d3edf0
diff --git a/core/store/dist/src/main/java/org/onosproject/store/mastership/impl/ConsistentDeviceMastershipStore.java b/core/store/dist/src/main/java/org/onosproject/store/mastership/impl/ConsistentDeviceMastershipStore.java
index 3c6e1c2..da8dda3 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/mastership/impl/ConsistentDeviceMastershipStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/mastership/impl/ConsistentDeviceMastershipStore.java
@@ -94,7 +94,7 @@
             new MessageSubject("mastership-store-device-role-relinquish");
 
     private static final Pattern DEVICE_MASTERSHIP_TOPIC_PATTERN =
-            Pattern.compile("device:(.*)");
+            Pattern.compile("^device:(.*)");
 
     private ExecutorService eventHandler;
     private ExecutorService messageHandlingExecutor;