repeatable dpkg-buildpackage

[George Shuklin <george.shuklin@gmail.com>]

Good day.

I'm playing with dpkg, but I got rather strange problem: Package can not 
be build second time after 1st package was build.


  dpkg-buildpackage -sa
....
dpkg-source: warning: newly created empty file 
'build/lib.linux-x86_64-2.7/neutron/api/__init__.py' will not be 
represented in diff
(100500 times for different files).

How can I to rebuild deb second time? It looks like I miss some cleanup 
command.

Thanks.