fixed no open connection during db.dropDatabase()

lib/db.js

@@ -70,15 +70,11 @@ db.Db = Db;
  */
 
 Db.prototype.drop = function (fn) {
-  var mdb = this._mdb;
-  
-  if(!this.connected) {
+  getConnection(this, function (err, mdb) {
     mdb.open(function () {
       mdb.dropDatabase(fn);
-    })
-  } else {
-    mdb.dropDatabase(fn);
-  }
+    });
+  });
 };
 
 /**
@@ -113,11 +109,33 @@ function Store(namespace, db) {
 }
 module.exports.Store = Store;
 
+function getConnection(db, fn) {
+  if(db.connected) {
+    fn(null, db._mdb);
+  } else if(db.connecting) {
+    db.once('connection attempted', function (err) {
+      fn(err, db._mdb)
+    });
+  } else {
+    db.connecting = true;
+    db._mdb.open(function (err) {
+      db.connecting = false;
+      db.emit('connection attempted', err);
+      if(err) {
+        db.connected = false;
+        throw err;
+      } else {
+        db.connected = true;
+        fn(null, db._mdb);
+      }
+    });
+  }
+}
+
 function collection(store, fn) {
-  var db = store._db
-    , mdb = db._mdb;
+  var db = store._db;
   
-  function execute(err) {
+  getConnection(db, function (err, mdb) {
     if(err) return fn(err);
     
     mdb.collection(store.namespace, function (err, collection) {
@@ -127,31 +145,8 @@ function collection(store, fn) {
       }
       
       fn(null, collection);
-    }); 
-  }
-  
-  function connect(fn) {
-    db.connecting = true;
-    mdb.open(function (err) {
-      db.connecting = false;
-      db.emit('connection attempted', err);
-      if(err) {
-        db.connected = false;
-        throw err;
-      } else {
-        db.connected = true;
-        fn();
-      }
     });
-  }
-
-  if(db.connected) {
-    execute();
-  } else if(db.connecting) {
-    db.once('connection attempted', execute);
-  } else {
-    connect(execute);
-  }
+  });
 }
 
 /**