Plperl Safe version check fails for Safe 2.09

It seems that the check in src/pl/plperl/plperl.c
 eval_pv((safe_version < 2.09 ? safe_bad : safe_ok), FALSE);

is not working quite as expected (CVS HEAD from today):

I have Safe.pm at version 2.09, yet any plperl function I run fails with :

ERROR:  error from function: trusted perl functions disabled - please 
upgrade perl Safe module to at least 2.09 at (eval 4) line 1.

Just to be sure I amended the test code to :
 elog(INFO, "Safe version = %f", safe_version); eval_pv((safe_version < 2.09 ? safe_bad : safe_ok), FALSE);

and I see :

INFO:  Safe version = 2.090000

(Followed by the error)

I confess some puzzlement - as the code *looks* like it should work!
The platform is Linux 2.4.22 glibc 2.3.2, perl 5.8.0 (Patched Redhat 9)

regards

Mark