Issue with tab-complete

I have an issue, in spigot.yml there is an option “tab-complete”, and as far as I know, when it is set to -1, tab-complete is not working at all, when set to 0, all tab-complete is working, and when it is set on 1, tab-complete should work after typing first letter. I have set this option to 1, and tab-complete is auto-completing everything. Is it a bug, or am I doing something wrong?