Delete invalid archives to prevent failing file copies later on

[maxhq]

This should fix #587

[stuartskelton]

This works for me.

[stuartskelton]

Looking into it a little more, the mirroring could be fixed a little more too,

EG,

In HTTP::Tinyish::Curl (which is the backend I am using)

We could ask for a file not to be saved, see https://stackoverflow.com/a/90009.

    my($output, $error);
    eval {
        run3 [
            $curl,
            $self->build_options($url, $opts),
            '-fO', # do not save a fail if there is a failure
            '-z', $file,
            '-o', $file,
            '--dump-header', $temp,
            '--remote-time',
            $url,
        ], \undef, \$output, \$error;
    };