The obit2 problem was My fault. When I created the package I left out the architecture info it is named orbit2-2.14.8-1vl59 and should be orbit2-2.14.8-i586-1vl59 the package manager cannot find it because of that.
Ah, so that's it. I thought it the problem was in the Thunderbird package dependencies...
It is.
if you look at the slack-required for thunderbird it requires
orbit2-2.14.8-1vl59 >=
while it should require
orbit2 >= 2.14.8
The Bad orbit2 package name causes it to look for something that it will never find.