Hello guys,
I needed to use unittest for raven, so I added it to android.p4a_whitelist. After compilation and installing the apk file, the application would get closed because there was an error: not being able to import 'unittest'.
For solving the problem, with help of tshirtman in IRC I included 'unittest/*' in the file:
my_project/.buildozer/android/platform/python-for-android/dist/<name_of_my_project>/whitelist.txt
So I guess the during compilation procedure Buildozer ignores android.p4a_whitelist in spec file.