Rbarlow 949186

This branch was made off of another branch of mine that has a separate pull request, so it would be best if you reviewed the one commit that is different rather than using the "Files Changed" tab in github:

https://github.com/pulp/pulp/commit/741dd4c66434d15e77719d0d8c9396a8c7a33154

This commit fixes a bug[0] that was causing us to automatically cancel any download that took more than five minutes to download.

This commit is important for our 2.1.1 release, so please review it quickly so we can get it merged to the 2.1 branch. This commit should also be merged to the master branch.

Again, please just review the one commit rather than this whole pull request, it'll make things easier.

[0] https://bugzilla.redhat.com/show_bug.cgi?id=949186