my $cnt = keys %{$self->{is_tested}};
        my $newenv = join $Config::Config{path_sep}, @dirs, @env;
        $CPAN::Frontend->optprint('perl5lib', sprintf ("Prepending blib/arch and blib/lib of ".
                                 "%d build dirs to PERL5LIB, reaching size %d; ".
                                 "for '%s'\n", $cnt, length($newenv), $for)
                                );
        $ENV{PERL5LIB} = $newenv;

##</code><code>##

#-> sub CPAN::is_tested
sub is_tested {
    my($self,$what,$when) = @_;
    unless ($what) {
        Carp::cluck("DEBUG: empty what");
        return;
    }
    $self->{is_tested}{$what} = $when;
}

##</code><code>##

sub _list_sorted_descending_is_tested {
    my($self) = @_;
    my $foul = 0;
    my @sorted = sort
        { ($self->{is_tested}{$b}||0) <=> ($self->{is_tested}{$a}||0) }
            grep
                { if ($foul){ 0 } elsif (-e) { 1 } else { $foul = $_; 0 } }
                    keys %{$self->{is_tested}};
    if ($foul) {
        $CPAN::Frontend->mywarn("Lost build_dir detected ($foul), giving up all cached test results of currently running session.\n");
        for my $dbd (sort keys %{$self->{is_tested}}) { # distro-build-dir
        SEARCH: for my $d (sort { $a->id cmp $b->id } $CPAN::META->all_objects("CPAN::Distribution")) {
                if ($d->{build_dir} && $d->{build_dir} eq $dbd) {
                    $CPAN::Frontend->mywarn(sprintf "Flushing cache for %s\n", $d->pretty_id);
                    $d->fforce("");
                    last SEARCH;
                }
            }
            delete $self->{is_tested}{$dbd};
        }
        return ();
    } else {
        return @sorted;
    }
}

##</code><code>##

#-> sub CPAN::reset_tested
# forget all distributions tested -- resets what gets included in PERL5LIB
sub reset_tested {
    my ($self) = @_;
    $self->{is_tested} = {};
}