Change version of tempest from >=17.1.0 to internal mcp/pike

Change-Id: I45e8ecd77eda670f0e4d669025c8d8582dbf15f8
diff --git a/requirements.txt b/requirements.txt
index 34fa1fd..df44099 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -17,6 +17,6 @@
 python-zaqarclient>=1.0.0 # Apache-2.0
 testtools>=2.2.0 # MIT
 testscenarios>=0.4 # Apache-2.0/BSD
-tempest>=17.1.0 # Apache-2.0
+git+https://gerrit.mcp.mirantis.net/packaging/sources/tempest@mcp/pike#egg=tempest # Tempest version from branch mcp/pike
 gabbi>=1.35.0 # Apache-2.0
 kombu!=4.0.2,>=4.0.0 # BSD