Anchor a tags self reference being filtered

[Érico Porto]

Anchor links, when the Markdown has references to it's own Headers, that result in HTML a tag links in the rendered file don't work. Currently if I have a

thispage.md

# headerk
content
# headerj
a [link to header k](thispage#headerk)

This works correctly inside github but the destination after the # get's filtered and disappears, resulting in a link to self.

We are having an issue with this here.