[RFC] vim-patch:7.4.229

```
Problem:  Using ":let" for listing variables and the second one is a
          curly braces expression may fail.
Solution: Check for an "=" in a better way. (ZyX)
```

https://code.google.com/p/vim/source/detail?r=839cca5ec18d560e3714065e54ed38b6e812aaf7