moving install dir back to /opt/local : what config files to edit?

["René J.V. Bertin"]

Before I first installed MacPorts, I created a symlink
ln -s /Volumes/WorkDisk/MacPorts /opt/local

and then let the installer do its thing. Or maybe I installed normally and then moved /opt/local to WorkDisk/MacPorts before creating the symlink, I cannot remember.

Anyway, there came a moment where for some reason I edited macports.conf to replace all /opt/local entries with /Volumes/WorkDisk/MacPorts . Apart from settling a possible issue that I can not remember (related to OS X resolving all those symlinks in its "rpath"s?), that change was (largely) transparent.

I just learned that this custom install location explains why I had to build all ports and updates from source, so I undid all my edits to macports.conf .

Result: I could install binary ports again (yay), but installing from source was no longer possible. The build process would try to put sources in _Volumes_Debian_MacPorts_var_macports_sources_rsync.macports.org_release_ports_* somewhere under /opt/local/var/macports/, and fail for lack of permissions. That's a bogus error message as 1) I used sudo and 2) I could perfectly well run the unpack command by hand.

So my question: what's going on here? /opt/local is still a symlink, so whatever port does, the sources still end up in the same place.
And more importantly: what file other than macports.conf would I need to edit (or what command to execute) in order to get source builds working again? For now I've gone back to the more correct definitions in macports.conf, but I'd really like to get back the ability to install binary packages...

Thanks,
René