Updating Release.tarball with a smaller file does not truncate the previous file

I assume the issue is similar to https://code.djangoproject.com/ticket/36191
I am not able to replicate this on a new Django project


If you upload a large file for the `Release.tarball` and save, then update this with a smaller file and save, these two files are not the same as the "smaller" file will have some junk on the end