The error itself seems to be that the system can’t find zlib (the library for gzipped IO.) The library ought to be in external/lib/z.lib, but it ships binary, and maybe it’s not compatible with your system.
The warnings at the top of the file are indicative of using python 2.6. I don’t think we “officially support” 2.6. I know that the developers downgrade recent OS X installations back to python 2.5 to avoid this problem.
So, you might need to get scons + python compatible again, or you might need to figure out why it can’t find zlib. Here are some suggestions:
A) Install zlib developer libraries. I know these are in the package repository (you know, synaptic, or apt-get install whatever). I’d try this first.
install scons 1.2. It’s probably in the package repository. It’s compatible with python 2.6; this will make the warnings go away and maybe/maybe not fix linker errors. (You’d need to use the locally installed scons, not the included-with-rosetta scons). You could also tweak the scons files (SConstruct or Sconscript or something) to look for python 2.5 instead of just “python”; I don’t know where this change would be but it’s likely to be simple (SCons documentation may help here.)