Leo P. Singer authored Oct 26, 2016 and Adam Mercer committed Dec 09, 2016

Seaborn imports pyplot, which configures the Matplotlib backend. So we must
set a non-X11 (e.g. agg or no-op) before importing Seaborn.
(cherry picked from commit 04a4b4a1c68378fe7169fdd49ecb2e256982341e)
Original: 55f24a7c6042001cac223ca22c9f4e3993ae0f6d