Ignore a common pattern that does not introduce any new information,
merely removes information.

Change-Id: I37da352c9295ec12b9dac7aad4b4792a6d726b0d
Reviewed-on: https://gerrit.libreoffice.org/64255
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>