util/scripts/gerrit-rebase: Improve error message

I received feedback that people were confused by "Error: foo", so
replace it with something more user friendly that serves the same
purpose.

Change-Id: I17b902a62020109e079437c8d9ffd7ea5979a3a1
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39274
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

util/scripts/gerrit-rebase

@@ -71,7 +71,7 @@ to_matches="$(git log ${common_base}..${to} | \
 	cut -d: -f2-)"
 
 # start rebase process, but fail immediately by enforcing an invalid todo
-GIT_SEQUENCE_EDITOR="echo foo >" \
+GIT_SEQUENCE_EDITOR="echo Ignore this error, it's intentional>" \
 	git rebase -i --onto ${to} ${from} ${to} 2>/dev/null
 
 # write new rebase todo