If the cwd of the task is also a cleandirs, you would see warnings from bitbake
about being unable to obtain cwd during the task execution. Tweak the code
to detect this and avoid the warnings.
(Bitbake rev: 6c7fd60c10955b0f23f64b25b5b4e154eb22a8f8)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>