make sure that 'before' event emitted from Request only once

src/core/request.js

@@ -44,13 +44,15 @@ Request.prototype.request = function(servers, callback_) {
   const callback = typeof servers === 'function' ? servers : callback_;
 
   this.emit('before');
+
+  const wasRequested = this.requested;
+  this.requested = true;
   this.callback(callback);
 
-  if (this.requested) {
+  if (wasRequested) {
     return this;
   }
 
-  this.requested = true;
   this.on('error', function() {});
   this.emit('request', this.remote);
 

test/request-test.js

@@ -1207,4 +1207,22 @@ describe('Request', function() {
       ]
     });
   });
+
+  it('Emit "before" only once', function(done) {
+    const remote = new Remote();
+    remote._connected = true;
+
+    const request = new Request(remote, 'server_info');
+
+    let beforeCalled = 0;
+
+    request.on('before', () => {
+      beforeCalled++;
+    });
+
+    request.request(function() {});
+    assert.strictEqual(beforeCalled, 1);
+    done();
+  });
+
 });