The stage-output role accepts a list of extensions to be replaced as txt
so that they can be seen directly from within a web browser.
Using a list means that children jobs cannot add to the parent setting,
only overwrite. Adding support for dicts while preserving, at least for
now, support for lists - to avoid breaking existing implementations.
This reverts change 844b3333aae02d596061386b5a1a2fbc821950be.
Change-Id: I5052c873f0a5da7ecaa38627e8900af86bbec2f9
Needed-By: https://review.openstack.org/539686
Needed-By: https://review.openstack.org/539708
Needed-By: https://review.openstack.org/539854