Node.traverse() was marked as deprecated since docutils-0.18.  Instead
of it, Node.findall() has been added as successor of traverse().

This applies a patch to docutils-0.17 or older to be available
Node.findall() and use it.

There is no docs and testcases for "None" argument of the program
directive.  It has been implemented since very old version.  But it's
not documented and tested long.

The implementation of the standard domain so far has considered the
first child of the rubric node is the title of the rubric.  But it can
may multiple nodes when the rubric title is marked up.

This extracts the title of the rubric from the whole of the children
of it.