>create databases "test1" -"test10" activate sharding
>create one collection "coll1" in each database + activate sharding (hashed shard key)
>insert documents

>drop databases

>ceate databases "test1" -"test10"..
>try activate sharding
=>

Command: { "shardCollection" : "test1.coll1" , "key" : { "_id" : "hashed"}}. Know error msg: already sharded

config.collections
{
  "_id" : "test1.coll1",
  "lastmod" : ISODate("1970-01-17T04:04:12.228Z"),
  "dropped" : true
}

in config.databases "test1"-"test10" is dropped.

SERVER-2253