Failures when rewriting request URLs generated by other extensions

When I install a userscript that depends on a javascript library whose url HTTPS Everywhere rewrites, Scriptish can't download the dependency. With the Scriptish master branch and the development version of HTTPS Everywhere, I get:

Error loading dependency: http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js
Error! Server returned: nothing (timed out)

Greasemonkey 0.9.3 also fails, but silently.

First reported here: https://github.com/erikvold/scriptish/issues/282 The download code is over there: https://github.com/erikvold/scriptish/blob/master/extension/modules/script/scriptdownloader.js

Trac:
Username: Tobu