Use of "^" (caret) in Subversion copy
===

I wanted to roll back my project to an earlier stage, so I tried this:

    svn rm -m "clear out mistakes rolling back" ^/MyProject/trunk
    svn copy -m "roll back" -r 165 ^/MyProject/trunk ^/MyProject/trunk

But I kept getting the error "File not found: revision 265, path '/MyProject/trunk'".  265 is HEAD, but I don't know why it would be looking for the target directory in an existing revision, rather than simply creating it.

Apparently the problem was with the ^ notation, because using complete URLs worked OK:

    svn copy -m "roll back" <full URL>/MyProject/trunk@165 <full URL>/MyProject/trunk

But I've used the ^ notation recently to make a branch via a similar copy operation.  (The client is command-line svn 1.6.17.)  So, why did it not work in this case?