RFR: 43: Repository.get should return Optional.empty on non-existing directory

[Erik Duveblad via github.com]

Hi all,

this small patch ensures that Repository.get returns Optional.empty() for non-existing paths.

Thanks,
Erik

## Testing
- [x] `sh gradlew test` on Linux x86-64

----------------

Commits:
 - 6f1cc929:	43: Repository.get should return Optional.empty on non-existing directory

Pull request:
http://git.openjdk.java.net/skara/pull/29

Webrev:
https://openjdk.github.io/cr/skara/29/webrev.00

Patch:
http://git.openjdk.java.net/skara/pull/29.diff

Fetch command:
git fetch https://github.com/openjdk/skara.git pull/29/head:pull/29