Tags should not change.That part I agree with.
+1 for removing those properties from branches.
I'm not going to make a case out of this, but please be aware the
implications of keeping the incorrect/outdated props on the tags:
I recognize that it's an inconvenience, yes, but note the same problem with tags exists in other forms -- e.g. there are hundreds of code comments pointing to the old issue tracker and mailing list URLs. The way I see it, we would not expect to modify tags to resolve those kinds of problem, just expect the reader to beware of such issues when working with old data, and so I feel we should apply that reasoning consistently even though it would be technically easy to modify the data.
all redundant SVN props removed from all branches in r1829788
FTR: Personally I see quite a difference between modifying/correcting project-wide SVN properties and modifying content/properties which one would consider being an inherent (logical) part of a tag. But I obviously this is not a non-controversial matter so I'm certainly fine with leaving this for tags as they are, of course. :-)