Fix "OK" button in "Target path is already used by another transfer." messagebox

When selecting to download a file over an existing file (that is currently being downloaded), a messagebox displaying "Target path is already used by another transfer.\nSelect another one." is being displayed. 

Issue:
Clicking on the "OK" button displays the messagebox again.

Expected:
Clicking on the "OK" button should allow the user to select a different download path.