Fix pool.query not invoking callback on connection error

fixes #872

Author: dougwilson

Changes.md

@@ -4,6 +4,10 @@ This file is a manually maintained list of changes for each release. Feel free
 to add your changes here when sending pull requests. Also send corrections if
 you spot any mistakes.
 
+## HEAD
+
+* Fix `pool.query` not invoking callback on connection error #872
+
 ## v2.4.0 (2014-07-13)
 
 * Add code `POOL_NOEXIST` in PoolCluster error #846

lib/Pool.js

@@ -169,7 +169,11 @@ Pool.prototype.query = function (sql, values, cb) {
   }
 
   this.getConnection(function (err, conn) {
-    if (err) return cb && cb(err);
+    if (err) {
+      var cb = query._callback;
+      cb && cb(err);
+      return;
+    }
 
     // Release connection based off event
     query.once('end', function() {

test/unit/pool/test-query-connection-error.js

@@ -0,0 +1,19 @@
+var assert = require('assert');
+var common = require('../../common');
+var pool   = common.createPool({port: common.fakeServerPort});
+var server = common.createFakeServer();
+
+server.listen(common.fakeServerPort, function (err) {
+  assert.ifError(err);
+
+  pool.query('SELECT 1', function (err, rows) {
+    assert.ok(err, 'got error');
+    assert.equal(err.code, 'ER_HOST_NOT_PRIVILEGED');
+    assert.equal(err.fatal, true);
+    server.destroy();
+  });
+});
+
+server.on('connection', function (conn) {
+  conn.deny('You suck.', common.Errors.ER_HOST_NOT_PRIVILEGED);
+});