I was trying to find out if the `deriv` method is covered by the unit tests.

Turns out it is, but the only way I was able to find this coverage information for this pull request was via the travis-ci log, which seems overly complicated:
https://travis-ci.org/astropy/astropy/jobs/18914850#L1843
https://coveralls.io/files/137268781#L229
@astrofrog Is there a better way of browsing to coverage information for astropy pull requests?