Fix branch for checkout

Related-prod: PRODX-3430
Change-Id: I4b6cf9e4b7aebabddfe0b2913e7578cd8d899664
diff --git a/pre-build.sh b/pre-build.sh
index f717c94..0167dd2 100644
--- a/pre-build.sh
+++ b/pre-build.sh
@@ -10,5 +10,5 @@
 HORIZON_LIB_REPO="${GERRIT_SCHEME}://${GERRIT_NAME}@${GERRIT_HOST_PORT}/packaging/sources/horizon"
 
 git clone ${HORIZON_LIB_REPO}
-cd horizon/ ; git checkout mcp/train
+cd horizon/ ; git checkout origin/mcp/train