Add fixed version for pip due upstream issue

https://github.com/pypa/pip/issues/5251

Change-Id: Idd1726e7e5d1d4953409ae697d259652f62c6fb8
Partial-Issue: https://mirantis.jira.com/browse/PROD-17449
diff --git a/Dockerfile b/Dockerfile
index 81fb489..7dbb524 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -32,6 +32,7 @@
   && apt-get update && apt-get  upgrade -y \
   && apt-get install -y vim-tiny git-core python-pip libffi-dev libssl-dev python-dev python3-dev iputils-ping patch
 
+#Due to upstream bug we should use fixed version of pip
 RUN pip install -U 'pip==9.0.3'
 WORKDIR /var/lib/
 # TODO migrate to downstrem mirror?