Test creating directory like `<property object at 0x7c7dd7379120>` under the tests directory

Running:

```
.../fab/tests$ python -m pytest -s -k test_missing_project ./system_tests/cui/
```
creates:
```
.../fab/tests$ ls -l fab-workspace/
total 4
drwxr-xr-x 2 joerg joerg 4096 Jun 26 19:05 ''
```
This likely invalid name should not be used, and the directory should be created in /tmp

Start by running the reported pytest command and inspect system_tests/cui/ for test_missing_project and the fab-workspace output. Trace where the property-object directory name and workspace path are chosen. Done means the test no longer creates that invalid-looking directory under tests and creates its workspace in /tmp instead.

Written by the indexing model from the issue text.