Firefox cache executable jars

Just observed one weird behavior of FireFox when it downloads an executable jar file. If you select "open" jar directly, the file size of downloaded jar file may be not correct in the FF Downloads window. It could display the old same jar file size. It means if you open the jar directly, the file size on the Download window can be different from the size you just save the file. I think it's a bug that FF is getting the wrong file size if opening executable jar. The reason is that in the ${userhome}/Local Settings/Temp directory, each time opening the executable jar from FF, it will create another file with "-" and number as suffix to the original file. If the file downloaded is updated with a newer version and newer size, then it still getting the size from the very original file. For example, abc.jar is firstly downloaded and opened. Then abc-1.jar will be the name if you download and open jar again. If abc-1.jar has a newer size, the FF Download window will show the size from abc.jar

https://bugzilla.mozilla.org/show_bug.cgi?id=518850