Previously this would be turned via `py.path.local("")` into the current
working directory.
This appears to be what `fspath = fn and py.path.local(fn) or None`
tries to avoid in `getfslineno`'s `TypeError` handling already, if
`Code` would raise it.
						
					
				
			 | 
			||
|---|---|---|
| .. | ||
| test_code.py | ||
| test_excinfo.py | ||
| test_source.py | ||