After reinstalling Lion, port install produces:
Warning: xcodebuild exists but failed to execute Error: Unable to open port: can't read "build.pre_args": can't read "build.cmd": Failed to locate 'gnumake' in path: '/opt/local/bin:/opt/local/sbin:/bin:/sbin:/usr/bin:/usr/sbin' or at its MacPorts configuration time location, did you move it?
and yet Xcode is just where it was:
> which gnumake /Developer4/usr/bin/gnumake
How can I avoid wiping out /opt and instead point MacPorts to build.pre_args, build.cmd, and gnumake?