+ Priority based; stable == 1, proposed-update == 2, etc.
+
+ i.e. A package targeted for a suite, must have a higher (or
+ equal) version number than anything in a suite with a lower
+ priority and also must have a lower (or equal) version number
+ than anything in a suite with a higher priorty. The checks are
+ always "or equal to" because two seperate uploads with the same
+ version will fail thanks to the file overwrite errors (at least
+ ignoring potato) and multi-suite uploads (e.g. "stable
+ unstable") need to work.