unable to checkout working tree

When I tried cloning the repository, it kept saying

```
error: unable to create file assets/test_2016-01-27 15:07:47.png: Invalid argument
error: unable to create file assets/test_2016-01-27 15:08:45.png: Invalid argument
error: unable to create file assets/test_2016-01-27 15:08:54.png: Invalid argument
error: unable to create file assets/test_2016-01-27 15:08:57.png: Invalid argument
error: unable to create file assets/test_2016-01-27 15:09:00.png: Invalid argument
error: unable to create file assets/test_2016-01-27 15:09:04.png: Invalid argument
error: unable to create file assets/test_2016-01-27 15:09:46.png: Invalid argument
error: unable to create file assets/test_2016-01-27 15:09:50.png: Invalid argument
fatal: unable to checkout working tree
warning: Clone succeeded, but checkout failed.
You can inspect what was checked out with 'git status'
and retry the checkout with 'git checkout -f HEAD'
```

What should I do? Am I doing something wrong?

Start with the listed assets/test_*.png paths and the Git clone output; inspect the checkout state with git status and retry the checkout command mentioned in the report. Done means identifying the cause of the checkout failure and recording a reproducible resolution for this repository.

Written by the indexing model from the issue text.