This is confusing from that article…
Solution: mount a long cage derailleur, for example the Ultegra 6800 long cage, which has a maximum cassette capacity of 32t.
The short cage has a capacity of 34t, the long cage 40t.
The question is, if you have 50/34, what is the max capacity of the long cage?..Shimano says is 34t, this guy says is 40t, but also says is 32t.