Calling

$.getScript("//www.server.com/script.js");

fails with an XMLHTTP Cross-Domain exception. The reason lies in the function ajax, line 2259:

if ( !s.url.indexOf("http") && s.dataType == "script" ) { 

This just checks for http(s) in the beginning, leaving out scheme-less URLs.

The fix is to change this line to be

if ( (!s.url.indexOf("http") || !s.url.indexOf("//")) && s.dataType == "script" ) { 

This also covers scheme-less URLs.

There might be other places in jQuery that have the same problem.