What I expected to happen was...:
Nothing

What actually happened was...:
It scrolled through names for the second argument, even though this causes a syntax error

Steps to Reproduce:
1. enter chat
2. type "/spawnpoint" (without quotes) and press space
3. press tab to enter a name for first argument and press space again
4. press tab again, this will result in the next argument becoming another name

Edit: also affects every version since