Disabling pinning is not working

[harikatakam]

I am trying to disable pinning of a column, but its not working.
and also found an similar issue in stakeoverflow , which is not answered yet. http://stackoverflow.com/questions/38582042/ui-grid-pinning-disabling-doesnt-work

[mportuga]

I was able to reproduce the issue here. It seems that once columns are defined, pinning can't be disabled.
http://plnkr.co/edit/DIMvDOuWc6LCR5WROpLa?p=preview