> I duly note in the bug tracker that I've checked in a fix, SVN revision 155234.
> The only formal record of the problem says it was fixed in revision 155234; my colleages note that trunk is now at 156974, and assume that the fix is in trunk.
This is the unrealistic part. The above assumes that you *and* your colleagues have never heard about branching in their entire life.
Everyone using SVN knows well that a revision number is meaningless without a branch. In the real (and centralized) world, you duly note in the bug tracker in which revision *and branch* you committed the fix. Even if you are clueless and forget the branch information, then your less incompetent colleagues will notice your mistake and find this information instantly in just one simple "svn log -r 155234" command: much easier than in decentralized, branching-fest system.