improves import of attachment https://bugs.documentfoundation.org/attachment.cgi?id=110836 from issue 62284

Change-Id: Icb056774746ce270138a54e9dfe9ca6987a64769
Reviewed-on: https://gerrit.libreoffice.org/14242Reviewed-by: Katarina Behrens <bubli@bubli.org>
Tested-by: Katarina Behrens <bubli@bubli.org>