nelstrom/vim-markdown-folding — pull request #4 by inkarkat (2012-12-13 13:51:54+00:00)
Title: FIX: Correct parsing for Setext-style header underline

According to John Gruber's spec and the Stack Overflow parser, the underlining of H1 / H2 using equal signs / dashes requires 1+ instances (not 3+), and the line must not contain anything else.