I'd like to run an older revision for my tester, without committing this test version. Is that possible? As usual, my tester doesn't have the time when I have a clean version of the project and I don't have a clean version of the project my when my tester has the time. He would of course like to test this version in the sandbox, which means that if I setup an older revision for him in the sandbox I will have to commit the older branch and correct me if I'm wrong as I still don't understand branching well enough, but doesn't this mean that my revision history will be 'corrupted' with older revision junk? Is this something that can be avoided and/or do I make a too big deal out of it?
I would just create a branch from the specific version that your tester wants to test. If after the test changes are needed you can change that in that branch. After the OK for a release you can deploy that version to the sandbox and then merge the change back to your main line. With this proces you always have a branch in production and you can keep developing in the main line.