I only had 8.1. And it turns out that 8.1 was a bit out of date. After updating to HEAD I could reproduce the behaviour you describe. A bisect shows that the change happened with this commit:
commit c0b9c747362c7624548a1892753c923e1c7426e4 Author: Arne Goedeke el@laramies.com Date: Thu Nov 10 16:21:04 2016 +0100
Stdio.File: simplified read()