}
    }
    if ($prereq[0][0] eq "perl") {
        my $need = "requires perl '$prereq[0][1]'";
        my $id = $self->pretty_id;
        $CPAN::Frontend->mywarn("$id $need; you have only $]; giving up\n");
        $self->{make} = CPAN::Distrostatus->new("NO $need");
        $self->store_persistent_state;
        return $self->goodbye("[prereq] -- NOT OK");
    } else {
        my $follow = eval {
            $self->follow_prereqs("configure_requires_later", @prereq);
        };
        if (0) {
        } elsif ($follow) {
            return;
        } elsif ($@ && ref $@ && $@->isa("CPAN::Exception::RecursiveDependency")) {
            $CPAN::Frontend->mywarn($@);
            return $self->goodbye("[depend] -- NOT OK");
        }
    }
    die "never reached";
}

#-> sub CPAN::Distribution::choose_MM_or_MB ;
sub choose_MM_or_MB {
    my($self,$local_file) = @_;
    $self->satisfy_configure_requires() or return;
    my($mpl) = File::Spec->catfile($self->{build_dir},"Makefile.PL");
    my($mpl_exists) = -f $mpl;
    unless ($mpl_exists) {
        # NFS has been reported to have racing problems after the
        # renaming of a directory in some environments.
        # This trick helps.
        $CPAN::Frontend->mysleep(1);
        my $mpldh = DirHandle->new($self->{build_dir})
            or Carp::croak("Couldn't opendir $self->{build_dir}: $!");
        $mpl_exists = grep /^Makefile\.PL$/, $mpldh->read;
        $mpldh->close;
    }
    my $prefer_installer = "eumm"; # eumm|mb
    if (-f File::Spec->catfile($self->{build_dir},"Build.PL")) {
        if ($mpl_exists) { # they *can* choose
            if ($CPAN::META->has_inst("Module::Build")) {
                $prefer_installer = CPAN::HandleConfig->prefs_lookup($self,
                                                                     q{prefer_installer});
            }
        } else {
            $prefer_installer = "mb";
        }
    }
    return unless $self->patch;
    if (lc($prefer_installer) eq "rand") {
        $prefer_installer = rand()<.5 ? "eumm" : "mb";
    }
    if (lc($prefer_installer) eq "mb") {
        $self->{modulebuild} = 1;
    } elsif ($self->{archived} eq "patch") {
        # not an edge case, nothing to install for sure
        my $why = "A patch file cannot be installed";
        $CPAN::Frontend->mywarn("Refusing to handle this file: $why\n");
        $self->{writemakefile} = CPAN::Distrostatus->new("NO $why");
    } elsif (! $mpl_exists) {
        $self->_edge_cases($mpl,$local_file);
    }
    if ($self->{build_dir}
        &&
        $CPAN::Config->{build_dir_reuse}
       ) {
        $self->store_persistent_state;
    }
    return $self;
}

#-> CPAN::Distribution::store_persistent_state
sub store_persistent_state {
    my($self) = @_;
    my $dir = $self->{build_dir};
    unless (File::Spec->canonpath(File::Basename::dirname($dir))
            eq File::Spec->canonpath($CPAN::Config->{build_dir})) {
        $CPAN::Frontend->mywarn("Directory '$dir' not below $CPAN::Config->{build_dir}, ".
                                "will not store persistent state\n");
        return;
    }
    my $file = sprintf "%s.yml", $dir;
    my $yaml_module = CPAN::_yaml_module;
    if ($CPAN::META->has_inst($yaml_module)) {
        CPAN->_yaml_dumpfile(
                             $file,
                             {
                              time => time,
                              perl => CPAN::_perl_fingerprint,
                              distribution => $self,
                             }
                            );
    } else {
        $CPAN::Frontend->myprint("Warning (usually harmless): '$yaml_module' not installed, ".
                                "will not store persistent state\n");
    }
}