This is caused by #920459 in texlive-extra. A workaround [1] that skips building refman.pdf was uploaded to Ubuntu.
[1] https://launchpad.net/ubuntu/+source/caffe/1.0.0+git20180821.99bd997-2ubuntu1 -- debian-science-maintainers mailing list [email protected] https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/debian-science-maintainers
