* upgrade from git on containers

* agreed with terms of DCO 1.1

Signed-off-by: Jorge Machado <jorge@jmachado.me>

installer/roles/image_build/files/Dockerfile.sdist

@@ -1,11 +1,12 @@
 FROM centos:7
 
-RUN yum install -y epel-release
+RUN yum -y update && yum -y install epel-release && yum -y install https://centos7.iuscommunity.org/ius-release.rpm
 
 RUN yum install -y bzip2 \
     gcc-c++ \
     gettext \
-    git \
+    git2u \
+    git2u-core \
     make \
     nodejs \
     python36-setuptools

installer/roles/image_build/templates/Dockerfile.j2

@@ -5,7 +5,7 @@ USER root
 ADD ansible.repo /etc/yum.repos.d/ansible.repo
 ADD RPM-GPG-KEY-ansible-release /etc/pki/rpm-gpg/RPM-GPG-KEY-ansible-release
 
-RUN yum -y update && yum -y install epel-release
+RUN yum -y update && yum -y install epel-release && yum -y install https://centos7.iuscommunity.org/ius-release.rpm
 
 # sync with tools/docker-compose/Dockerfile
 RUN yum -y install acl \
@@ -16,7 +16,8 @@ RUN yum -y install acl \
   cyrus-sasl-devel \
   gcc \
   gcc-c++ \
-  git \
+  git2u \
+  git2u-core \
   krb5-devel \
   krb5-libs \
   krb5-workstation \