This illustrates bug 19910.
There is a space behind the defective header, i.e. three equals and a space, then newline. If you remove the space, this page renders more usefully, and working section edit links are shown.
Text in section A. More text in section A.
Text in section B. More text in section B.
Text in broken section C. More text in broken section C.
Text in section D. More text in section D.
--Purodha Blissenbach 15:19, 24 July 2009 (UTC)