[Vimperator] how do I purge the command line history?

[Sitaram Chamarty]

I've tried everything, setting history=0, setting it to 10, closed and
re-opened the browser multiple times.  Nothing works.  The command
line history, (as seen by pressing ":" then up-arrows) remains.

[One of the items is a password that I mistakenly typed in due to not
being in pass-through mode, and this is sometimes a shared system.
Hence my concern...]