exclude option not working in combination with warn-unversioned

I have a setup like this
````
% tree
.
├── notarepo (Not a repo by accident)
├── repo1 (git repo)
├── repo2 (git repo)
└── target (build output, will never be a git repo)

4 directories, 0 files
`````
I was trying to ignore the target folder with the exclude option, but it wasn't excluded. 
`````
% clustergit --warn-unversioned --exclude=target
Starting git status...
Scanning sub directories of .
./notarepo                              : Not a GIT repository
./repo1                                 : Changes
./repo2                                 : Changes
./target                                : Not a GIT repository
Done
`````

With this fix, exclusions work with or without --warn-unversioned

`````
% clustergit --warn-unversioned --exclude=target
Starting git status...
Scanning sub directories of .
./notarepo                              : Not a GIT repository
./repo1                                 : Changes
./repo2                                 : Changes
Done
````