The previous commit was injecting a generator object instead of
a string, which happened to fix the issue but we should fix it
properly! Thanks to Christopher Larson for spotting.
(Bitbake rev: 36589f13c5babb3b2af82666c8a96338e6ea4eb9)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>