LIBRARY_PATH not used before /usr/lib anymore in gcc 4.2 and later?

[Frederik <freggy at gmail dot com>]

I've got different versions of the boost libraries installed on my 
system: one is installed system wide in /usr/lib64, while other versions 
are installed in /cvos/shared/apps/boost/gcc-4.[123]/1.35.0, compiled 
with the respective different versions of gcc.

When I want to use one of the custom built libraries, I set the CPATH, 
LIBRARY_PATH and LD_LIBRARY_PATH variables to the respective include 
files and libraries.

For the gcc 4.1 one, this works correctly:
$ g++ -o test test.cpp -lboost_regex
$ ldd test | grep boost
        libboost_regex.so.1.35.0 => /cvos/shared/apps/boost/
gcc-4.1/1.35.0/lib/libboost_regex.so.1.35.0 (0x00007f2352ad1000)

And without the environment vars set, it links against the one in /usr/
lib64:
        libboost_regex.so.2 => /usr/lib64/libboost_regex.so.2 
(0x00007fb000918000)

However when I do exactly the same with gcc 4.2 and gcc 4.3, it always 
links against the libboost_regex.so.2 on in /usr/lib64 and not against 
the libboost_regex.so.1.35.0 in /cvos/shared/apps/boost/gcc-4.[23]/1.35.0/
lib, even though the LIBRARY_PATH and LD_LIBRARY_PATH variables have this 
directory set as first.

The versions used are gcc 4.1.2 20070626 (Red Hat 4.1.2-14), stock gcc 
4.2.4 and stock gcc 4.3.1.

Has this behaviour changed in gcc 4.2, or is it something RH specific 
which makes that it works with my gcc 4.1?

-- 
Frederik