Nope, when i change this we get a test failure:

```
[Jekyll::FatalException] exception expected, not
Class: <TypeError>
Message: <"no implicit conversion of nil into String">
---Backtrace---
/Users/schneems/Documents/projects/jekyll/lib/jekyll/post.rb:163:in `join'
/Users/schneems/Documents/projects/jekyll/lib/jekyll/post.rb:163:in `rescue in process'
/Users/schneems/Documents/projects/jekyll/lib/jekyll/post.rb:158:in `process'
````

Looks like `@dir` and `@name` can both be nil.