debuild clean failed

[Tong Sun <suntong001@users.sourceforge.net>]

Hi,

`debuild clean` failed for me strangely:

    $ debuild clean
     dpkg-buildpackage -us -uc -ui clean
    dpkg-buildpackage: error: unknown option or argument clean

    Use --help for program usage information.
    debuild: fatal error at line 1182:
    dpkg-buildpackage -us -uc -ui clean failed

I *think* I've never configured `dpkg-buildpackage` myself, so I'm
wondering where does such `dpkg-buildpackage -us -uc -ui clean` come
from?
and how to fix it?

thx