nova: drop pypowervm dependency

Nova depends on pypowervm for POWER architecture support. But it is
unmaintained upstream and breaks CentOS builds (wants to install Py2
only 'futures' package).

Closes-bug: #1955034

Change-Id: Ife9385c93239e910db2e4405ec4661f667357bc0
(cherry picked from commit 7de91fd)

Author: hrw

docker/nova/nova-base/Dockerfile.j2

@@ -101,7 +101,10 @@ ADD plugins-archive /
     '/plugins/*'
 ] %}
 
+# NOTE(hrw): nova lists powervm in requirements and it wants 'futures' on py3.6 which can not be installed.
+# So let drop it as we do not support POWER architecture.
 RUN ln -s nova-base-source/* nova \
+    && sed -i -e "/^pypowervm/d" nova/requirements.txt \
     && {{ macros.install_pip(nova_base_pip_packages | customizable("pip_packages")) }} \
     && mkdir -p /etc/nova/ \
     && cp -r /nova/etc/nova/* /etc/nova/ \

releasenotes/notes/nova-drop-pypowervm-256048c2a9cd594d.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Nova images are built without ``pypowervm`` package. It is needed only for
+    POWER architecture support (which we do not support) and breaks CentOS
+    builds by trying to install (Python 2 only) 'futures' package.