In listing blocks (set off by rows of dashes), the usual
formatting characters of asciidoc are instead rendered verbatim.
When the escaped double-hyphen of olden days is moved into such a
block along with other formatting improvements, it becomes
backslash-dash-dash.
So we remove the backslash.
Signed-off-by: Jonathan Nieder <jrnieder@uchicago.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>