Versions 1.4+ no longer automatically set cache to false if undefined.

The culprit seems to be this line:

if ( s.dataType == "script" && s.cache == null )
    s.cache = false;

which was updated to:

if ( s.dataType === "script" && s.cache === null ) {
    s.cache = false;
}

which no longer evaluates to true (s.cache is undefined, so == will evaluate to true, whereas === to false).

No big deal, but maybe this should be noted in the documentation, and/or code removed since it's no longer doing anything.

Only semi-related ticket I could find was this:

http://bugs.jquery.com/ticket/3004