Modifying an Impress Template

[Samuel Mehrbrodt]

Hi,

I need to modify an default Impress template to fix [1].

I guess, when I edit it in Impress, information like Author, last 
changed etc. will be saved there.
I could unzip it, edit the xml and zip it again, but in both cases there 
will be no meaningful diff, since it's a ZIP file.

What is the best way to do this?

Samuel

[1] https://bugs.freedesktop.org/show_bug.cgi?id=59396