It is required for python-flask.
Of course, this is problem ... I have missed that python-jinja2 is actually in the real RHEL, not in EPEL.
However, python-jinja2-2.6-1 from Fedora 16 is buildable on EL-6 with python-sphinx10 just with one line changed, make docs must read
make -C docs html SPHINXBUILD=sphinx-1.0-build
There's a python-jinja2-26 up for review.
Given bug 757895 being fixed, this could happily end in WONTFIX