/usr/share/go-1.10/test/fixedbugs/bug409.out is in golang-1.10-src 1.10.1-1ubuntu2.
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