Canon 50 1.4. Green and purple artifacts

I got my 50 1.4 a more then year ago was never happy with wide open because of
green and purple halo around bright contrast objects! And I thought I
got defected lens and never used it at 1.4-1.8!

But recently my friend got one and to my surprise he has same effect!
So what that suppose to mean?! I thought 50 1.4 one of the best
affordable lens, but I a bunch of situation it just completely
unusable!!!!!

Samples below are from Canon XSi: