Comment 4 for bug 1501651

Culprit in qemu code:
http://git.qemu.org/?p=qemu.git;a=blob;f=linux-user/signal.c;h=1141054be2170128d6f7a340b41484b49a255936;hb=HEAD#l82

Proposed fix (that was never merged):
https://codereview.appspot.com/124900043/diff/60001/src/pkg/runtime/os_linux.c

I was able to hack /usr/lib/go/src/runtime/os1_linux.go as follows:
< if rt_sigaction(uintptr(i), &sa, nil, unsafe.Sizeof(sa.sa_mask)) != 0 {
---
> if rt_sigaction(uintptr(i), &sa, nil, unsafe.Sizeof(sa.sa_mask)) != 0 && i != 64 {

After rebuilding the binary, this allowed the test case to pass.