panic: Mutex bug somewhere

[shazow]

Running the v1.2 tag:

^Apanic: runtime error: index out of range
        panic: sync: unlock of unlocked mutex

goroutine 2760 [running]:
panic(0x774180, 0xc420446580)
        /usr/local/Cellar/go/1.7rc1/libexec/src/runtime/panic.go:500 +0x1a1
sync.(*Mutex).Unlock(0xc420212d90)
        /usr/local/Cellar/go/1.7rc1/libexec/src/sync/mutex.go:111 +0x104
panic(0x7945e0, 0xc42000e0e0)
        /usr/local/Cellar/go/1.7rc1/libexec/src/runtime/panic.go:458 +0x243
github.com/shazow/ssh-chat.(*Host).AutoCompleteFunction.func1(0xc42041f3b0, 0x49, 0x0, 0xc400000009, 0x49, 0xc42041f3b0, 0x49, 0x593d19)
        /Users/shazow/local/go/src/github.com/shazow/ssh-chat/host.go:222 +0x4b5
golang.org/x/crypto/ssh/terminal.(*Terminal).handleKey(0xc420212d80, 0x9, 0x100, 0x0, 0x9)
        /Users/shazow/local/go/src/golang.org/x/crypto/ssh/terminal/terminal.go:546 +0x585
golang.org/x/crypto/ssh/terminal.(*Terminal).readLine(0xc420212d80, 0x8340b0, 0xc420212d90, 0xc420452e30, 0xc420452e20)
        /Users/shazow/local/go/src/golang.org/x/crypto/ssh/terminal/terminal.go:707 +0x173
golang.org/x/crypto/ssh/terminal.(*Terminal).ReadLine(0xc420212d80, 0x0, 0x0, 0x0, 0x0)
        /Users/shazow/local/go/src/golang.org/x/crypto/ssh/terminal/terminal.go:664 +0xa4
github.com/shazow/ssh-chat.(*Host).Connect(0xc420102500, 0xc420212d80)
        /Users/shazow/local/go/src/github.com/shazow/ssh-chat/host.go:135 +0x431
github.com/shazow/ssh-chat.(*Host).Connect-fm(0xc420212d80)
        /Users/shazow/local/go/src/github.com/shazow/ssh-chat/host.go:185 +0x34
github.com/shazow/ssh-chat/sshd.(*SSHListener).Serve.func1(0xc4200fe330, 0x9bb860, 0xc420022558)
        /Users/shazow/local/go/src/github.com/shazow/ssh-chat/sshd/net.go:64 +0x69
created by github.com/shazow/ssh-chat/sshd.(*SSHListener).Serve
        /Users/shazow/local/go/src/github.com/shazow/ssh-chat/sshd/net.go:65 +0xac

[shazow]

Autocomplete is disabled on the chat2 server until this is fixed.

[shazow]

This can be reproduced with Autocomplete enabled by running a server, joining with at least one user, then running cat /dev/urandom | ssh ... a few times.