A report on WSSSPE5.1 and the state of sustainable research software is now available:

D. S. Katz, S. Druskat, R. Haines, C. Jay, A. Struck, “The State of Sustainable Research Software: Results from the Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE5.1),” arXiv:1807.07387 [cs.SE], 2018.