thx for the hints.
The simple.t failed because of an insecure $ENV{PATH} when running under -T. -T stands for "enable tainting checks".
hmmm - Perl goes into paranoid mode and obsessively/compulsively does run-time checking of all the paths of execution that the script could take; hence it's looking at all the paths and not getting any. we'll need to set $ENV{PATH} something like this