hdima/vim-scripts — pull request #5 by inkarkat (2013-10-22 14:05:11+00:00)
Title: ENH: Special highlighting for first (summary) line and following blank line.

This ensures that the summary line doesn't get too long, and it alerts the user when the second line (which separates the summary from any following longer text) contains text.

Taken from Tim Pope's syntax/gitcommit.vim.