This is a very strange bug, I am not even sure that it is a kernel problem, but enlightenment developers blame kernel, so here I am.
I am using Gentoo and upgraded kernel to 4.11.0. Since then, su and sudo does not work on enlightenment session, but no problem what so ever in console.
No other desktop environment is affected.
If it helps, there are some discussions/bug reports:
Created attachment 256613 [details]
Git Bisect log
Ran a git bisect and found the code responsible for su/sudo error since 4.11
I can not say where the problem is (enlightenment or kernel) so, please advise me.
This has been fixed in kernel 4.11.5 by "ptrace: Properly initialize ptracer_cred on fork".