fix bytes/str handling when looking for file content
fix bytes/str handling when looking for file content

The tests were passing unicode but in some cases the real code was
passing bytes, so accept both and do the encoding ourselves if we need
to.

Change-Id: I0f64d301b36207b1ffa6503e8c27f679cdf6516f
Signed-off-by: Doug Hellmann <0798ebecfb7bc4dfb9d0445c2fa030eb64e1fa1c@doughellmann.com>

openstack/reno