my $muxs = $ssh->get_ctl_path;
ok(-S $muxs, "mux socket exists");
is((stat $muxs)[2] & 0777, 0600, "mux socket permissions"); # line 92
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Have you worked through the troubleshooting section of Net::OpenSSH? Chances are you're hitting this permissions problem for good reason.

Update: 448 in base 8 is 700. Speak to your systems administrator if in doubt