bitbake -b core-image was showing no matches when it should list all targets
containing the fragment "core-image". This patch only calls os.path.abspath()
on things that look like paths and passed the path around more consistently to
various functions to get this use case working again.
(Bitbake rev: 6e9119c42d3f4cb3dab3d25856eee8b4bf4ad94f)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>