When I tried to update texi2html through homebrew on my mac, it returned the error message. I found that I tried to access to http://download.savannah.gnu.org/releases/texi2html/texi2html-1.82.tar.gz, and then was forwarded to http://mirror.yongbok.net/nongnu//texi2html/texi2html-1.82.tar.gz, and got 404.
I can avoid this error and can install texi2html, but wanted to notice that somehow anther slash is inserted between "nongnu" and "texi2html" when forwarded to yongbok.net mirrow.