adt-run [11:00:25]: host seb-e6410; command line: /usr/bin/adt-run software-properties -U --apt-pocket=proposed --- qemu adt-xenial-i386-cloud.img

(process:19074): GLib-WARNING **: /build/glib2.0-Q50eE3/glib2.0-2.47.5/./glib/gmem.c:483: custom memory allocation vtable not supported
qemu: could not load PC BIOS 'bios-256k.bin'
Unexpected error:
Traceback (most recent call last):
  File "/usr/share/autopkgtest/python/VirtSubproc.py", line 707, in mainloop
    command()
  File "/usr/share/autopkgtest/python/VirtSubproc.py", line 645, in command
    r = f(c, ce)
  File "/usr/share/autopkgtest/python/VirtSubproc.py", line 263, in cmd_open
    caller.hook_open()
  File "/usr/bin/adt-virt-qemu", line 498, in hook_open
    wait_boot()
  File "/usr/bin/adt-virt-qemu", line 111, in wait_boot
    echo=args.show_boot)
  File "/usr/share/autopkgtest/python/VirtSubproc.py", line 244, in expect
    block = sock.recv(4096)
ConnectionResetError: [Errno 104] Connection reset by peer
adt-run [11:00:25]: ERROR: testbed failure: cannot send to testbed: ['BrokenPipeError: [Errno 32] Broken pipe\n']