The module unittest-xml-reporting overwrites sys.stdout with an StringIO() object and when cooker is called it throws a traceback:

======================================================================
ERROR [18.025s]: test_testexport_basic (oeqa.selftest.runtime-test.TestExport)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/mlopezva/repo/poky/meta/lib/oeqa/selftest/runtime-test.py", line 34, in test_testexport_basic
    with runqemu('core-image-minimal') as qemu:
  File "/usr/lib64/python3.4/contextlib.py", line 59, in __enter__
    return next(self.gen)
  File "/home/mlopezva/repo/poky/meta/lib/oeqa/utils/commands.py", line 217, in runqemu
    tinfoil = bb.tinfoil.Tinfoil()
  File "/home/mlopezva/repo/poky/bitbake/lib/bb/tinfoil.py", line 54, in __init__
    self.cooker = BBCooker(self.config, features)
  File "/home/mlopezva/repo/poky/bitbake/lib/bb/cooker.py", line 233, in __init__
    fd = sys.stdout.fileno()
io.UnsupportedOperation: fileno