Percent (%) sign inserted into URLs using LaTeX's url package

Here I describe a quick hack from this comp.text.tex post (via Google Groups) to ensure that long URLs (longer than 72 characters) in LaTeX's \url{} package don't have an added percent (%) sign.

Follow up:

If you use LaTeX's URL package (\url{}) you might notice that long URLs in BiBTeX files get screwed up... that is, in URLs longer than 72 characters, an extra percent (%) sign is added to the URL. The best way I've seen to fix this is a quick little hack mentioned on this comp.text.tex post (via Google Groups). Essentially you add the following after the \usepackage{url} statement in your .tex file:

\begingroup \makeatletter \g@addto@macro{\UrlSpecials}{% \endlinechar=13 \catcode\endlinechar=12 \do%{\Url@percent}\do^^M{\break}} \catcode13=12 % \gdef\Url@percent{@ifnextchar^^M{@gobble}{\mathbin{\mathchar`%}}}% \endgroup %

While I'm not entirely certain what this piece of magic does, it does remove the errant percent (%) signs from URLs in BiBTeX entries.