BibField: fix for misbehavior when parsing rules
BibField: fix for misbehavior when parsing rules

Signed-off-by: Esteban J. G. Gabancho <03cb568148df368b792a31d9c4d06b12dc802700@cern.ch>
Co-authored-by: Lars Holm Nielsen <7eaffca9f7cd98839b5821d0d23e09ff764b82cd@cern.ch>
Tested-by: Tibor Simko <c7116e45300b163846dc01f3ed02116e3f8ef7a5@cern.ch>

tiborsimko/invenio,tiborsimko/invenio,inveniosoftware/invenio,inveniosoftware/invenio