issue2551046: Attempts to attach file or create large message fail under python2 This patch fixes a bug introduced for working around an issue in python3. There were a few ways to fix this, but I think this fix: 1) follows the spirit of the original patch 2) follows python programming expectations I am still having an issue trying to get both code paths executed from the test suite. The super code path is not tested, but I did validate that path from the browser and it works producing valid uploaded files in both python 2 and 3. Thanks to Ezio Melotti and Joseph Myers for their help in guiding me to come up with this solution.