I'm trying to build perl 5.003_03 on a RH 6.1 machine (i686 arch). Perl is failing its AnyDBM module test (which is a perl interface to the ndbm (libdb.so) library). The test assigns and reads a value on a tied hash using a null key ($h{''}). When building perl on a RH 5.2 system using glibc 2.0.7, this test works fine, but on our RH6.1 machine (glibc 2.1.2) it fails because the assignment just doesn't work (the null key is never added to the hash). So, on 5.2, the perl code: $h{''} = 'foo'; print "$h{''}\n"; will print "foo". But on 6.1 it prints an empty line. It looks like this is a bug in the libdb library (although I'm not 100% certain).
Take a look at the patch we have integrated into the perl RPM from RH 6.1 to see a possible workaround for Perl's problems on fuguring out which library is which.