Change build id to OPENMASTER

Change-Id: Ib1b2ea0303619753dace8a776295ad4e1ceab096
diff --git a/core/build_id.mk b/core/build_id.mk
index ffff91e..e954794 100644
--- a/core/build_id.mk
+++ b/core/build_id.mk
@@ -23,7 +23,7 @@
 # (like "TC1-RC5").  It must be a single word, and is
 # capitalized by convention.
 #
-BUILD_ID := JB_MR2
+BUILD_ID := OPENMASTER
 
 # DISPLAY_BUILD_NUMBER should only be set for development branches,
 # If set, the BUILD_NUMBER (cl) is appended to the BUILD_ID for