sh/merge-with-custom-msg: 'origin' handling fix [ci skip]
sh/merge-with-custom-msg: 'origin' handling fix [ci skip]

The KERNEL_CHANGED and PILLS_CHANGED variables used the revision with
'origin' stripped from it (intended for using in messages only), which
caused them to miss remote revisions.

Also tweaks the conditional so that the kernel diff only displays when
pills haven't been updated.

jfranklin9000/urbit,ngzax/urbit,jfranklin9000/urbit,urbit/urbit,jfranklin9000/urbit,urbit/urbit,ngzax/urbit,ngzax/urbit,jfranklin9000/urbit,urbit/urbit,urbit/urbit,ngzax/urbit,urbit/urbit,jfranklin9000/urbit,urbit/urbit,ngzax/urbit,jfranklin9000/urbit,urbit/urbit,ngzax/urbit,ngzax/urbit,jfranklin9000/urbit