Bukkit

What steps will reproduce the problem?
1. negating /back in permissions
2. executing /back

What is the expected output? What do you see instead?
"you do not have permission!" is expected. It does say that, but still sends you back to your previous location

What version of the product are you using?
v8.7

Do you have an error log of what happened?
No erros in command console

Please provide any additional information below.
no matter how permissions are configured /back will work. no permissions set at all, negated permissions etc.

Will look into this, thanks for the report.