ghc-pkg: can't unregister - not found - describe works?

marc@localhost /pr/source/wxh/wxhaskell-0.9.4 $ ghc-pkg-wrapper-6.6.1 unregister wx ghc-pkg: cannot find package wx marc@localhost /pr/source/wxh/wxhaskell-0.9.4 $ ghc-pkg-wrapper-6.6.1 describe wx name: wx version: 0.10.1 license: AllRightsReserved [...] What does happen here? ghc-pkg-wrapper is just a simple script defining GHC_PACKAGE_PATH marc@localhost /pr/source/wxh/wxhaskell-0.9.4 $ ghc-pkg-wrapper-6.6.1 list /nix/store/q74q9piy9fsk4k7w1p3r3xc8wsm1z87m-ghc-6.6.1/lib/ghc-6.6.1/package.conf: Cabal-1.1.6.2, HUnit-1.1.1, QuickCheck-1.0.1, base-2.1.1, [...] /nix/store/fbj85ijnbc69bh19zi1a14p9idknb5g9-wxHaskell-0.10.1-pre20070124/nix-support/package.conf: wx-0.10.1, wxcore-0.10.1 Marc