Re: I've implemented MATLABs bwmorph('thin',...): any interest?

I made a PR: https://github.com/scikit-image/scikit-image/pull/1858 Travis builds for Python >2.7 are failing because of a warning about a duplicate citation in my inline docs--how can I fix this? WARNING: duplicate citation R311, other instance in /home/travis/build/scikit-image/scikit-image/doc/source/api/skimage.restoration.txt