Recursivity bomb when copying a directory into itself

You have a directory called "dir1" which contains a file called "file1":

dir1/file1

AjaXplorer will let you copy dir1 into itself. When trying to accomplish this, it will create recursive copies like this:

dir1/file1
dir1/dir1/file1
dir1/dir1/dir1/file1
dir1/dir1/dir1/dir1/file1
...