Comment 1 for bug 1634519

The local QEMU run also doesn't time out cleanly:

qqemu-system-x86_64: /build/qemu-3KpUoe/qemu-2.6.1+dfsg/hw/char/serial.c:231: serial_xmit: Assertion `!(s->lsr & UART_LSR_TEMT)' failed.
autopkgtest [16:03:27]: ERROR: timed out on command "[...]" (kind: test)
autopkgtest [16:03:28]: test ubuntu-regression-suite: -----------------------]
Traceback (most recent call last):
  File "/tmp/autopkgtest-virt-qemu._36vlf46/runcmd", line 63, in <module>
    s.connect('/tmp/autopkgtest-virt-qemu._36vlf46/ttyS1')
ConnectionRefusedError: [Errno 111] Connection refused

I. e. it also breaks the status of ttyS1 somehow.