Backports.convert_to_path didn't survive "Split all backports individually 🎉", but it's still referenced in v3.1.0 IO.binread`. That's not so 🎉
bobthecow/genghis#85 is a thing it broke.
The offending commit is here: 846bd09
v3.1.1: Fix IO.binread [#71]
Thanks for the bug report.
I'm very sorry about this. I didn't realize it, but IO.binread can not actually run any of the rubyspecs written for that method because there's a before & after that play around with encoding. That's why the tests didn't detect the problem.
Fixed in 3.1.1.
Maybe I could fake some of the encoding stuff, or include separate tests, or use a fork of Rubyspecs... Not sure yet.