Temporary hack to build image with Stcklight  with 2019.2.0 version

Change-Id: I3726244725de96cd870ded834d333c154629ab9b
Related-Prod: #PROD-29193(PROD:29193)
diff --git a/Dockerfile b/Dockerfile
index 960ec96..3a8e5cd 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -11,7 +11,7 @@
 USER root
 ARG UBUNTU_MIRROR_URL="http://archive.ubuntu.com/ubuntu"
 ARG SL_TEST_REPO='http://gerrit.mcp.mirantis.com/mcp/stacklight-pytest'
-ARG SL_TEST_BRANCH='master'
+ARG SL_TEST_BRANCH='release/2019.2.0'
 
 WORKDIR /var/lib/
 COPY bin/ /usr/local/bin/