tpope/vim-markdown — pull request #38 by hjdivad (2013-05-02 19:11:11+00:00)
Title: Clear `main_syntax` if we set it.

This prevents conflicts with other syntaxes that use `main_syntax`, like
vim-javascript.

Fixes an issue when vim-javascript and vim-markdown are both loaded in which
loading a markdown file prevents all future JavaScript buffers from using
conceal.