First and most important: The wiki describes the behavior of X-COM, the original. Not OpenXcom.
Second: There are many differences between X-COM and OpenXcom. They are not very visible, unless you look for them, but they're there... hundreds of them!
To answer questions:
1/ wiki lies? ... probably not, but I didn't test this specific behavior in X-COM, feel free to test and let us know
2a/ is this a bug? ... in OpenXcom, no... there is nothing in the source code that would indicate an intention to implement something like that
2b/ is this a bug? ... in X-COM, nobody knows... maybe except Julian Gollop... my personal guess would be that it is a bug
3/ is it because of superhuman?... no
4/ please explain why is it not working according to wiki... see first two lines on the top