py_package_preprocess() was using relative paths which mean it depends on
exactly what directory it starts in. To clarify the code, always use absolute
paths.
(From OE-Core rev: d9941a2d9b423af2ca3313e8c1357ccfcc9a96a5)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>