(Not really answering your question, but) it does seem like a long time for a simple bug to be open, but there are several developer releases, and maybe he's just being careful about what gets released. I'd do the patch differently anyway, moving the first call to build_subs outside of new() so the first bunch of subs get defined upon use of the module, and change the body of the sub to:

foreach my $attrib (@_) {
  no strict 'refs';
  *$attrib = sub {
    my $self = shift;
    $self->{$attrib} = shift if @_;
    return $self->{$attrib};
  } unless defined &$attrib;
}
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But maybe that's just MHO :-)

Oh, and to answer your question, I think a lot of people just ignore warnings in their error logs :-)