The "modify" command allows to replace an existing record (its
text value). The primary key is the name of the record. If
duplicity or missing record detected, throw error.
Tests in networkxml2xmlupdatetest.c contain replacements of an
existing DNS-text record and failure due to non-existing record.
Resolves: https://gitlab.com/libvirt/libvirt/-/issues/639
Signed-off-by: Adam Julis <ajulis@redhat.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>