Merge branch 'js/rebase-i-shortopt'

"git rebase -i" learned to take 'b' as the short form of 'break'
option in the todo list.

* js/rebase-i-shortopt:
  rebase -i: recognize short commands without arguments

t/lib-rebase.sh

@@ -49,7 +49,7 @@ set_fake_editor () {
 		case $line in
 		pick|squash|fixup|edit|reword|drop)
 			action="$line";;
-		exec*|break)
+		exec*|break|b)
 			echo "$line" | sed 's/_/ /g' >> "$1";;
 		"#")
 			echo '# comment' >> "$1";;