Also correct two comments, and move slash_re from _revision_key() to
the module top level (together with the new sha1_re).
(Bitbake rev: 98cad8636e9c82bc40a033bb83633ec994758eb0)
Signed-off-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>