[CONJS-196] 3.0 regression on release connection #195

In 3.0, when releasing connection to pool not with connection.release() but connection.close(), connection wasn't given back to pool, but killed.
When killing connection, server send a ER_CONNECTION_KILLED error that can sometime be caught by connector before socket is closed, but that's not assured, then having just an ER_SOCKET_UNEXPECTED_CLOSE error.

Author: rusher

lib/pool-callback.js

@@ -96,9 +96,8 @@ class PoolCallback extends EventEmitter {
       .getConnection(cmdParam)
       .then((baseConn) => {
         const cc = new ConnectionCallback(baseConn);
-        cc.end = (cb) => {
-          cc.release(cb);
-        };
+        cc.end = (cb) => cc.release(cb);
+        cc.close = (cb) => cc.release(cb);
         cb(null, cc);
       })
       .catch(cb);

lib/pool-promise.js

@@ -86,6 +86,7 @@ class PoolPromise extends EventEmitter {
         return new Promise(baseConn.release);
       };
       conn.end = conn.release;
+      conn.close = conn.release;
       return conn;
     });
   }