Guard against the absence of path segments.

Closes #288 

```
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] Picasso (Parent) .................................. SUCCESS [0.857s]
[INFO] Picasso ........................................... SUCCESS [9.616s]
[INFO] Picasso Pollexor Transformer ...................... SUCCESS [3.018s]
[INFO] Picasso Sample .................................... SUCCESS [6.493s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 20.958s
[INFO] Finished at: Tue Oct 22 11:28:31 PDT 2013
[INFO] Final Memory: 46M/540M
[INFO] ------------------------------------------------------------------------
```