LaTeX not always rendered in Markdown cells in ipython notebooks

Short description

Gitlab 9.1 RC has landed with support for IPython notebook rendering.

However, when in Markdown cell, some typical syntax from IPython notebook does not work.

I have set up a project for tests and the notebook file is here: https://gitlab.com/zabugr/test-ipython/blob/master/markdown.ipynb

How it looks like:

Expected:

Moving this issue here from discussion in the !10017 (merged)