Finish 2732

This finishes (and superceeds) the work in #2732.
@jehturner implemented a fix to #2700 already that was almost ready for merging. I cloned this branch and literally only moved two lines of text in the changelog entry.

@jehturner : I've cloned you branch so that you will get proper credit for your contribution to astropy. Thanks for making this fix! I don't want to "steal" your branch, but I want to make sure that this PR does not get lost and that we can merge it soon before 0.4.3 and soon 1.0 will be released.

@astrofrog : See my comment in #2732. I believe that no new test is required. I rebased onto the current master, so hopefully Travis will pass and this can be merged soon.

closes #2732 
closes #2700