Fix the matching of key name for unique keys with numbers as name in mysql. Closes #2303

lib/dialects/mysql/query.js

@@ -53,7 +53,7 @@ module.exports = (function() {
 
 
     switch (err.errno || err.code) {
     switch (err.errno || err.code) {
       case 1062:
       case 1062:
-        match = err.message.match(/Duplicate entry '(.*)' for key '(.*?)'$/);
+        match = err.message.match(/Duplicate entry '(.*)' for key '?(.*?)$/);
 
 
         return new sequelizeErrors.UniqueConstraintError({
         return new sequelizeErrors.UniqueConstraintError({
           fields: null,
           fields: null,