Right now you can't really set anything to "undef" using Bugzilla::Object->update, because it uses string comparisons to check if things have changed. It's possible to re-write the function to accept setting things to undef, and in fact I've done it in a customization for a client, I just have to pull out the code and attach it here as a patch.
Created attachment 257184 [details] [diff] [review] v1 Okay, this applies, and I know that it worked just fine in the customizations. I know that the if/else is weird, but that's the *only* way that I could find that actually worked. I'm pretty sure it's the only logic that works.
Comment on attachment 257184 [details] [diff] [review] v1 I cannot find any better way to work around these undefined values, so r=LpSolit.
Yeah, the logic is weird, but it's the only thing that works. Checking in Bugzilla/Object.pm; /cvsroot/mozilla/webtools/bugzilla/Bugzilla/Object.pm,v <-- Object.pm new revision: 1.12; previous revision: 1.11 done