User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1) Gecko/20090630 Firefox/3.5 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3 After the release of 3.6.x, the way Javascript scripts are being executed causes Firefox to call resources on the page that respond with an HTTP 301 or 302 multiple times, even when they are only referenced once on the page. This seems to be unique to resources that are returned by the web server with an HTTP redirect; items that are returned with HTTP 200 are not affected. The items referenced in the Location header of the request are also not affected; it is just the redirect itself that is called multiple times. Reproducible: Always Steps to Reproduce: Go to http://bsizemore-test.appspot.com/bugs/test3.html and use an HTTP monitor like LiveHTTPHeaders, Firebug, or another. The problem will be intermittent if you use http://bsizemore-test.appspot.com/bugs/test2.html If you use http://bsizemore-test.appspot.com/bugs/test1.html, you will not see the behavior. The only difference between these three is the number of <script> tags on the page. Note that test.js does nothing. Actual Results: You will see that when refreshing the page, you get TWO requests for the redirect image (redirect.png) instead of the one. Expected Results: Expect to see each resource on the page requested ONCE, not multiple times.

The log in comment 1 doesn't show the problem, in fact; it shows us reading the 302 from cache. But depending on the exact timing of the loads this _could_ happen if the real load races wth the prefetch load (which is triggered by the scripts). The prefetch not properly priming the image cache in the redirect case is bug 552605.