Make log location more explicit in error message
Make log location more explicit in error message

See https://github.com/QubesOS/qubes-issues/issues/4224#issuecomment-414513721.

marmarek/qubes-core-admin,QubesOS/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin