It seems that in CKAN 2.8.0, the c.action attribute is at least sometimes missing when templates are being rendered. I can reproduce this for the home/index.html template, which currently breaks ckanext-pages for CKAN 2.8.0 (see ckan/ckanext-pages#78).

It seems that this is a consequence of a change to routing.py as part of #3891, although I'm not sure about that.