Fix PythonTest on windows

Change-Id: I8d9d2757020fe4d2cf51bfd257e4bcb573baaaf5
Reviewed-on: https://gerrit.libreoffice.org/11631
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>