What I need is that the latest (mistake) revision being reverted and that the repository does not store it in anyway. That is, I'm trying to erase the latest revision out of existence, NOT trying to fix things by coming back to the latest-1 revision. In other words, I want to avoid the repository growing in size.
Suppose head revision is 100. I knew that the suggested answer is that
svnadmin dump -r0:80 old-repo | svnadmin load --force-uuid new-repo.
What I'm confusing myself about is why not
svnadmin dump -r81:100 old-repo
Why the first and not the second solution? I suppose svnadmin dump will erase the repository completely? And keeping only revision 0 - 80 in a dump file? Is my understanding of "taking a part out of the repository into a dump file" about svnadmin dump completely wrong? (That is revision 81 - 100 is still there)
Sincere apologies if this has been asked. I did spend some time searching though no specific things about this were found. A topic link in case I miss it would be greatly appreciated.