Ported tripleo-modify-image to py3

It makes yum and pip installs work with py3 packages. The package manager
dnf/yum and pip binary are determined at run time from the OS.

Use dnf-plugins-core for dnf with respect to
yum-plugin-priorities.

Use pipefail with set -ex to fix linter errors.

Change-Id: I997509204e30abb8b21ef936ea44440fbaa5a0e4
Closes-Bug: #1813546

files/dev_install.sh

@@ -1,4 +1,4 @@
-set -e
+set -eou pipefail
 
 # Cherry-pick a refspec
 # $1 : project name e.g. keystone

files/rpm_install.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-set -ex
+set -eox pipefail
 
 rpm -Uvh /tmp/*.rpm
 rm -f /tmp/*.rpm

files/yum_update.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-set -eux
+set -eoux pipefail
 
 packages_for_update=
 if [ -n "$1" ] && command -v repoquery >/dev/null 2>&1; then
@@ -14,6 +14,13 @@ if [ -z "$packages_for_update" ]; then
     exit
 fi
 
-yum install -y yum-plugin-priorities
-yum -y update $packages_for_update
-rm -rf /var/cache/yum
+PKG="$(command -v dnf || command -v yum)"
+PKG_MGR="$(echo ${PKG:(-3)})"
+
+if [ $PKG_MGR == "dnf" ]; then
+    $PKG install -y dnf-plugins-core
+else:
+    $PKG install -y yum-plugin-priorities
+fi
+$PKG -y update $packages_for_update
+rm -rf /var/cache/$PKG_MGR

templates/Dockerfile-dev.j2

@@ -4,6 +4,12 @@ LABEL modified_append_tag={{ modified_append_tag }}
 USER root
 
 COPY refspec_projects /root/refspec_projects
-RUN /bin/bash -c 'rpm -qi python-pip || yum install -y python-pip; cd /; for X in $(ls /root/refspec_projects/*.tar.gz); do pip install $X; done; rm -Rf /root/refspec_projects'
+RUN /bin/bash -c 'PKG="$(command -v dnf || command -v yum)"; \
+    PKG_MGR="$(echo ${PKG:(-3)})"; \
+    if [ $PKG_MGR == "dnf" ]; then $PKG install python3-pip; PIP=pip3; else $PKG install python-pip; \
+    PIP=pip; fi; \
+    cd /; \
+    for X in $(ls /root/refspec_projects/*.tar.gz); do $PIP install $X; done; \
+    rm -Rf /root/refspec_projects'
 
 USER "{{ original_user }}"