Fixed a bug causing all connection attempts to fail if the first connection attempt failed

lib/dialects/abstract/connection-manager.js

@@ -18,6 +18,7 @@ ConnectionManager = function(dialect, sequelize) {
   this.sequelize = sequelize;
   this.sequelize = sequelize;
   this.config = config;
   this.config = config;
   this.dialect = dialect;
   this.dialect = dialect;
+  this.versionPromise = null;
 
 
   if (config.pool) {
   if (config.pool) {
     config.pool = _.clone(config.pool); // Make sure we don't modify the existing config object (user might re-use it)
     config.pool = _.clone(config.pool); // Make sure we don't modify the existing config object (user might re-use it)
@@ -199,10 +200,13 @@ ConnectionManager.prototype.getConnection = function(options) {
         return self.sequelize.databaseVersion(_options).then(function (version) {
         return self.sequelize.databaseVersion(_options).then(function (version) {
           self.sequelize.options.databaseVersion = semver.valid(version) ? version : self.defaultVersion;
           self.sequelize.options.databaseVersion = semver.valid(version) ? version : self.defaultVersion;
 
 
-          self.versionPromise = undefined;
+          self.versionPromise = null;
 
 
           self.$disconnect(connection);
           self.$disconnect(connection);
         });
         });
+      }).catch(function (err) {
+        self.versionPromise = null;
+        throw err;
       });
       });
     }
     }
   } else {
   } else {