get with content_file hangs forever in master

[cgaspar]

Firefox 40.0.3, MacOS 10.10.5, MozRepl-0.06 perl module, MozRepl::RemoteObject 0.39, MozRepl 1.1.2.1-signed plugin

use WWW::Mechanize::Firefox;

my $ua = WWW::Mechanize::Firefox->new( repl => '127.0.0.1:42042' ) || die;

my $resp = $ua->get('http://www.example.com/', ':content_file' => '/tmp/example.html'); print STDOUT "get returned $resp->code()\n";

The file is downloaded, but the get method never returns - it just keeps busy waiting forever.