在跑2c用例时，打印的log出现了这种error或者warn的日志，虽然test pass了，但代码应该是有问题的，请问一下出现这种问题大概是为啥呢？
[error] failed to generate snapshot!!!, [regionId: 1, err : stat /tmp/test-raftstore019092993/snap/gen_1_5_5_default.sst.tmp: no such file or directory]
[warning] failed to load existent snapshot meta when try to build /tmp/test-raftstore209586016/snap/gen_1_5_5_(default|write|lock).sst: invalid CF number of snapshot meta, expect 3, got 0
[warning] failed to delete snapshot /tmp/test-raftstore209586016/snap/gen_1_5_5_(default|write|lock).sst because it’s already registered elsewhere
[error] failed to generate snapshot!!!, [regionId: 1, err : invalid CF number of snapshot meta, expect 3, got 0]
2c的用例还全都pass了
