/usr/share/go-1.8/test/fixedbugs/bug409.out is in golang-1.8-src 1.8.3-2ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1
+1.000000e+000 +2.000000e+000 +3.000000e+000 +4.000000e+000