Bug: Removing all collections from a databases throws an error box

When the last collection in a databases is removed (on Linux) an error is raised:

Title: Collection operation failed
Content: Database error:

{ "serverUsed:" : "ip", "ns" : "namespace", "nIndexesWas" : nIndexes, "ok" : 0.0, "errmsg" : "can't drop system ns", "code" : 20}