port diagnose fails on 10.6.8

[Jan Stary]

This is MacPorts 2.4.1 on a mac mini running 10.6.8.
'port diagnose fails like this:

Error: process_cmd failed:
Usage: xcode-select -print-path
   or: xcode-select -switch <xcode_folder_path>
   or: xcode-select -version
      Arguments:
    -print-path                     Prints the path of the current Xcode folder
    -switch <xcode_folder_path>     Sets the path for the current Xcode folder
    -version                        Prints xcode-select version information
child process exited abnormally

I am using XCode 3.2.6, the latest available fo 10.6.8.
Apparently, the xcode-select call has changed somehow.

        Jan