Message 278111 - Python tracker

Ah, I misunderstood your comment is about Sphinx's internal DOM.

Sphinx has own pot and po files.

In case of custom extension, `sphinx-build -b gettext` doesn't extract
messages from Python code. That's why I used dummy html template.

Another way is adding custom make target, which runs `sphinx-build -b gettext`
and custom command to generate another pot from pyspecific extension.