Some shell pwd implementations default to the "Logical" PWD, which can contain symlinks. The POSIX standard for /bin/pwd is to return the "Physical" PWD with all symlinks resolved. Some shells don't support the -P option the the built-in pwd, so we don't want to reply on that. For some reason, we're redefining the PWD env variable which should by the phyical path, but I'm not really interested in tracking down all the windy history for this. Basically, this bit me once, and now it's fixed.