Comment 1 for bug 1813001

On Precise 3.13
$ cat /proc/self/stack
cat: /proc/self/stack: Permission denied
$ sudo cat /proc/self/stack
[<ffffffff810730b0>] do_wait+0x1f0/0x280
[<ffffffff8107403f>] SyS_wait4+0xaf/0x120
[<ffffffff817823fc>] system_call_fastpath+0x26/0x2b
[<ffffffffffffffff>] 0xffffffffffffffff
$ ls -l /proc/self/stack
-r--r--r-- 1 ubuntu ubuntu 0 Jan 24 04:06 /proc/self/stack

But on Bionic, the file permission is:
$ ls -l /proc/self/stack
-r-------- 1 ubuntu ubuntu 0 Jan 24 12:07 /proc/self/stack