use latest revision for diffs on section=new

When adding a new section to a page with section=new and then using "Show Changes" the diff is against the version, on which the edit based. But for a new section you can ignore this information in the diff, because you get never a edit conflict. It is also not necessary to see in the diff that other users has change other sections.

Feel free to modify the patch.

Thanks.

Version: 1.20.x
Severity: normal

Attached: