build_rpm.sh: fix building tar ball for puppet repos carrying setup.py
build_rpm.sh: fix building tar ball for puppet repos carrying setup.py

puppet repositories from OpenStack carry setup.py to take advantage of
the automation for release notes. So avoid to consider them as python
repositories by checking metadata.json.

Change-Id: I4de7f83bed2b5f676c5fe4ec7ae7f3ed550da2ce

openstack-packages/DLRN,openstack-packages/delorean,openstack-packages/delorean,openstack-packages/DLRN