After reading this:
It made me realize that the Drupal core behavior of aggregating libraries jQuery (and in D7 jQuery UI) together with all the other JS is potentially a significant performance suck for Drupal core. The reason - if I change one byte of JS that's in the aggergated JS (or add a new query string), all users have to re-download jQuery and jQuery UI again. Further if my home page and inner page have slightly different JS aggregated together, I end up downloading the libraries multiple times in aggregated form.
I propose that JS added as a library should (at least by default) never be aggregated and not get the query string added. We must, though, put the library version number in the file name.
The original issue has already been sorted, and the current patch merely changes variable names for consistency with core and sets the default stale file threshold to three days.
PASSED: [[SimpleTest]]: [MySQL] 40,569 pass(es).
FAILED: [[SimpleTest]]: [MySQL] 40,567 pass(es), 0 fail(s), and 2 exception(s).
PASSED: [[SimpleTest]]: [MySQL] 35,921 pass(es).
FAILED: [[SimpleTest]]: [MySQL] Unable to apply patch 721400-variable-names-158-retest.patch. Unable to apply patch. See the log in the details link for more information.