Save a reference to the bound version of onProcessExit so we can properly unbind it

lib/dialects/abstract/connection-manager.js

@@ -39,7 +39,8 @@ ConnectionManager = function(dialect, sequelize) {
   if (config.pool.maxConnections) config.pool.max = config.pool.maxConnections;
   if (config.pool.minConnections) config.pool.min = config.pool.minConnections;
 
-  process.on('exit', this.onProcessExit.bind(this));
+  this.onProcessExit = this.onProcessExit.bind(this); // Save a reference to the bound version so we can remove it with removeListener
+  process.on('exit', this.onProcessExit);
 };
 
 ConnectionManager.prototype.onProcessExit = function() {