scripts/create-pull-request: fix putting subject containing / into cover letter
If a single-commit series had a shortlog containing a "/" character then
that prevented putting the shortlog into the subject of the cover letter
message. Use a different separating character with the sed command (one
much less likely to appear) in order to fix it.
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
