Merge branch 'us/printf-not-echo'

* us/printf-not-echo:
  test-lib.sh: do not "echo" caller-supplied strings
  rebase -i: do not "echo" random user-supplied strings

git-rebase--interactive.sh

@@ -749,7 +749,7 @@ rearrange_squash () {
 					;;
 				esac
 			done
-			echo "$sha1 $action $prefix $rest"
+			printf '%s %s %s %s\n' "$sha1" "$action" "$prefix" "$rest"
 			# if it's a single word, try to resolve to a full sha1 and
 			# emit a second copy. This allows us to match on both message
 			# and on sha1 prefix