sys.stdout.detach does not work when debuilding

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ERROR: test_devel_version (snapcraft.tests.test_main.TestMain)
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Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/mock/mock.py", line 1305, in patched
    return func(*args, **keywargs)
  File "/home/sergiusens/source/github.com/ubuntu-core/snapcraft/snapcraft/tests/test_main.py", line 92, in test_devel_version
    snapcraft.main.main()
  File "/home/sergiusens/source/github.com/ubuntu-core/snapcraft/snapcraft/main.py", line 98, in main
    log.configure()
  File "/home/sergiusens/source/github.com/ubuntu-core/snapcraft/snapcraft/log.py", line 45, in configure
    sys.stdout.detach(), encoding='UTF-8', line_buffering=True)
io.UnsupportedOperation: detach

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We should treat it as an istty call returning False