Came here to report this. Good that I'm not the only one affected.

The log:
nb@home:~/.local/opt/factorio$ cat factorio-current.log
0.000 2016-09-15 21:25:24; Factorio 0.14.6 (build 24690, linux64, alpha)
0.006 Operating system: Linux (Gentoo n/a)
0.006 Program arguments: "./factorio"
0.006 ...