if and when it fails tests perlbrew will tell you how to force install

Yeah ... I didn't mention this in the above rambling rant, but when it first failed to install (because of the test failures) I noticed the following advice at the end of the messages:

Generally, if you need to install a perl distribution known to have mi
+nor test
failures, do one of these commands to avoid seeing this message:

  perlbrew --notest install perl-5.6.2
  perlbrew --force install perl-5.6.2
[download]

So, I re-ran the command with --force but it still failed in exactly the same way.
Then I noticed another message higher up:

If some perl tests failed and you still want to install this distribut
+ion anyway,
do:

  (cd /home/sisyphus/perl5/perlbrew/build/perl-5.6.2/perl-5.6.2; make 
+install)
[download]

So I did that, and it installed that build of perl-5.6.2 just fine.

Cheers,
Rob