0.10.0 breaks sphinx_gallery.load_style

[pmeier]

I'm using an exotic setup where the gallery built requires GPUs and thus cannot be run by RTD or the like (see #704) for details. I have a built server set up that builds the galleries and packages them, whereas the normal CI falls back to downloading these pre-built galleries. For that to work, the built server runs with sphinx_gallery.gen_gallery whereas the normal CI runs with sphinx_gallery.load_style.

This worked fine until 0.9.0. With 0.10.0 images scraped with the default matplotlib scraper now use the .. image-sg:: introduced in #808. Unfortunately, this directive is not loaded when using sphinx_gallery.load_style. You end up with warnings like these:

.. image-sg:: /galleries/examples/beginner/images/sphx_glr_example_nst_without_pystiche_003.png
   :alt: Input image
   :srcset: /galleries/examples/beginner/images/sphx_glr_example_nst_without_pystiche_003.png
   :class: sphx-glr-single-img
/home/philip/git/pystiche/pystiche/docs/source/galleries/examples/beginner/example_nst_without_pystiche.rst:1305: WARNING: Unknown directive type "image-sg".

The build goes through, but the images are not shown in the HTML version.

[pmeier]

Here are two RTD builds, that for the purpose of this issue only differ in the sphinx-gallery version:

• 0.9.0: docs, log
• 0.10.0: docs, log

[larsoner]

@pmeier I think we need to add the directive when doing load-style. Could you make a PR to fix it?