[automerger] Return error for invalid reorder parameter am: 4286d31e9e am: df2bef9a86 am: e7950035a8 am: b596887685 am: 3d1c41dfb1 am: a5af46e7c4 am: a01ece8616 am: a4843b0735 am: 884157609f am: 8c56e181af am: 2dba4eec8f am: 2456efeb9c
am: 83e278f9f8

Change-Id: Ieed6a7b61af43bc2d29020f8e4b4a361bd0533cb