sequelize/sequelize — pull request #988 by KevinMartin (2013-10-12 20:12:21+00:00)
Title: Fix "Cannot call method 'toLowerCase' of undefined" error

```
sequelize/lib/dao.js:139
ap(function(d) { return d.toLowerCase() }).indexOf(values[attrName].toLowerCas
^
TypeError: Cannot call method 'toLowerCase' of undefined
```

Problem occurs when the MySQL enum field (attrName) is not being inserted or updated.