Version bump to OPM4.171019.020

Change-Id: I8bf4fc193376f2b5328cca0bb5384c3c975a8793
diff --git a/core/build_id.mk b/core/build_id.mk
index e09a8ae..5fb6c5a 100644
--- a/core/build_id.mk
+++ b/core/build_id.mk
@@ -18,4 +18,4 @@
 # (like "CRB01").  It must be a single word, and is
 # capitalized by convention.
 
-export BUILD_ID=OPM4.171019.019
+export BUILD_ID=OPM4.171019.020