bitbake: build: Handle conflict between cwd and cleandirs

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>

bitbake/lib/bb/build.py

@@ -197,6 +197,8 @@ def exec_func(func, d, dirs = None):
         for cdir in d.expand(cleandirs).split():
             bb.utils.remove(cdir, True)
             bb.utils.mkdirhier(cdir)
+            if cdir == oldcwd:
+                os.chdir(cdir)
 
     if flags and dirs is None:
         dirs = flags.get('dirs')