#1803 spam control search fails with certain strings

[Kai Schätzl]

The "Find spam control rules matching" search fails
searching for a single "0" (zero). I have seen it recently
also display too few items when searching for "au".
Suddenly after adding a new item the search showed
more hits. I wasn't able to repro this, but the "0"
problem is easily reproducable.

[Jamie Cameron]

Logged In: YES
user_id=129364

This is a bug caused by Perl treating the string '0' as
false, and thinking that nothing was entered to search for.
I will fix it in the next release ..
Let me know if you can re-produce the 'au' search bug though ..