Spurious panic when AVAHI not running

- Bus 001 Device 010: resetting HP Color LaserJet FlowMFP M578
  USB[0]: closed
  USB[1]: closed
  USB[2]: closed
  USB[3]: closed
- Bus 001 Device 010: removed HP Color LaserJet FlowMFP M578
! PNP Bus 001 Device 010: AVAHI: Bad state
fatal error: unexpected signal during runtime execution
[signal SIGSEGV: segmentation violation code=0x80 addr=0x0 pc=0x7f36c46da3db]

runtime stack:
runtime.throw(0x765893, 0x2a)
    /usr/lib/go/src/runtime/panic.go:1116 +0x72
runtime.sigpanic()
    /usr/lib/go/src/runtime/signal_unix.go:726 +0x4ac

goroutine 19 [syscall]:
runtime.cgocall(0x6c3da0, 0xc00004cb50, 0xc000342700)
    /usr/lib/go/src/runtime/cgocall.go:133 +0x5b fp=0xc00004cb20 sp=0xc00004cae8 pc=0x40715b
main._Cfunc_libusb_bulk_transfer(0x7f36c46e9c00, 0xc00038cc82, 0xc0002a6000, 0x2000, 0xc00038cc30, 0x0, 0x0)
    _cgo_gotypes.go:606 +0x4d fp=0xc00004cb50 sp=0xc00004cb20 pc=0x6b84cd
main.(*UsbInterface).Recv.func1(0xc00009a080, 0xc0002a6000, 0x2000, 0x2000, 0xc00038cc30, 0x0, 0x7721d0)
    /home/tteras/oss/ipp-usb/usbio_libusb.go:638 +0xc5 fp=0xc00004cba8 sp=0xc00004cb50 pc=0x6c1445
main.(*UsbInterface).Recv(0xc00009a080, 0xc0002a6000, 0x2000, 0x2000, 0x0, 0xc00004cc90, 0x1, 0x1)
    /home/tteras/oss/ipp-usb/usbio_libusb.go:638 +0x8f fp=0xc00004cc18 sp=0xc00004cba8 pc=0x6be66f
main.(*usbConn).Read(0xc00009c090, 0xc0002a6000, 0x2000, 0x2000, 0x0, 0x0, 0x0)
    /home/tteras/oss/ipp-usb/usbtransport.go:595 +0x227 fp=0xc00004cd28 sp=0xc00004cc18 pc=0x6b5bc7
bufio.(*Reader).Read(0xc0000a2060, 0xc0002a6000, 0x2000, 0x2000, 0x6ed120, 0xc000080801, 0xc0002a6000)
    /usr/lib/go/src/bufio/bufio.go:213 +0x142 fp=0xc00004cd78 sp=0xc00004cd28 pc=0x567f02
net/http.(*body).readLocked(0xc0000c23c0, 0xc0002a6000, 0x2000, 0x2000, 0x6defe0, 0xc00000e540, 0x0)
    /usr/lib/go/src/net/http/transfer.go:833 +0x5f fp=0xc00004cdd8 sp=0xc00004cd78 pc=0x66333f
net/http.(*body).Read(0xc0000c23c0, 0xc0002a6000, 0x2000, 0x2000, 0x0, 0x0, 0x0)
    /usr/lib/go/src/net/http/transfer.go:825 +0xf9 fp=0xc00004ce40 sp=0xc00004cdd8 pc=0x663259
io/ioutil.devNull.ReadFrom(0x0, 0x7f369d8c71f8, 0xc0000c23c0, 0x706780, 0x72cb01, 0x7f369d948ca0)
    /usr/lib/go/src/io/ioutil/ioutil.go:144 +0x92 fp=0xc00004ceb0 sp=0xc00004ce40 pc=0x5846b2
io/ioutil.(*devNull).ReadFrom(0x9a1f80, 0x7f369d8c71f8, 0xc0000c23c0, 0x7f369d948ca0, 0x9a1f80, 0x1)
    <autogenerated>:1 +0x50 fp=0xc00004cef0 sp=0xc00004ceb0 pc=0x584d10
io.copyBuffer(0x7bc520, 0x9a1f80, 0x7f369d8c71f8, 0xc0000c23c0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
    /usr/lib/go/src/io/io.go:395 +0x2ff fp=0xc00004cf68 sp=0xc00004cef0 pc=0x4a24df
io.Copy(...)
    /usr/lib/go/src/io/io.go:368
main.(*usbResponseBodyWrapper).Close.func1(0xc0000c2400)
    /home/tteras/oss/ipp-usb/usbtransport.go:491 +0xab fp=0xc00004cfd8 sp=0xc00004cf68 pc=0x6bf00b
runtime.goexit()
    /usr/lib/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc00004cfe0 sp=0xc00004cfd8 pc=0x46dde1
created by main.(*usbResponseBodyWrapper).Close
    /home/tteras/oss/ipp-usb/usbtransport.go:483 +0xc7

goroutine 1 [select]:
main.PnPStart(0x7f36c4708200, 0x0)
    /home/tteras/oss/ipp-usb/pnp.go:127 +0x3b1
main.main()
    /home/tteras/oss/ipp-usb/main.go:244 +0x52c

goroutine 6 [syscall]:
main._Cfunc_libusb_handle_events(0x7f36c47082b0, 0xc000000000)
    _cgo_gotypes.go:838 +0x49
main.libusbContext.func3.1(0x0)
    /home/tteras/oss/ipp-usb/usbio_libusb.go:132 +0x58
main.libusbContext.func3()
    /home/tteras/oss/ipp-usb/usbio_libusb.go:132 +0x25
created by main.libusbContext
    /home/tteras/oss/ipp-usb/usbio_libusb.go:129 +0x136

goroutine 8 [syscall]:
os/signal.signal_recv(0x0)
    /usr/lib/go/src/runtime/sigqueue.go:147 +0x9d
os/signal.loop()
    /usr/lib/go/src/os/signal/signal_unix.go:23 +0x25
created by os/signal.Notify.func1.1
    /usr/lib/go/src/os/signal/signal.go:150 +0x45
OpenPrinting / ipp-usb

Spurious panic when AVAHI not running #20
