Join result takes on the calling from index
https://github.com/pandas-dev/pandas/issues/15582

Fixes indexing referenced in 15582. Tests appear to work on my end, we'll see...
really? https://travis-ci.org/pandas-dev/pandas/jobs/208041268 Apparently i don't know how to run tests properly -_-

Still gettin the hang of this :/ @sleepdeprivation you can push additional changes to this branch. Just make sure to reopen if you want to keep working on it.