When dropping files into a directory with spaces into its name, A duplicate directory with %20s is created

Steps to reproduce:

1. Create a new davros grain
2. Create a directory with a space in its name, e.g. `A Directory`.
3. Enter that directory.
4. Drop some files into the directory.
5. Go back up

There will then be two directories:

- `A Directory`
- `A%20Directory`

The files will be in the former; the latter will be empty.