above=[anything but bottom] expands all the way to the top

[GoogleCodeExporter]

What steps will reproduce the problem?

\headerbox{}{name=a,column=0,above=bottom}{}
\headerbox{}{name=b,column=0,above=a}{}

What is the expected output? What do you see instead?
I expect boxes 'a' and 'b' to be as high as needed for their content.
This happens for 'a', but 'b' expands all the way to the top.


What version of the product are you using? 
Latest change is from 29. September 2011

On what operating system?
Debian testing 
GNU/Linux 3.1.4 x86_64
Latex 3.1415926-1.40.10 from package TeX Live 2009-15
pgf 2.10-1

Original issue reported on code.google.com by [email protected] on 1 Dec 2011 at 4:01