Fix python26Packages.sqlite3
haskell-yi-custom: use NIX_* vars for nicer wrap

According to @bennofs , this should now work regardless of what kind of
mess the user is in.
Merge pull request #4646 from geerds/python26-sqlite3

Fix python26Packages.sqlite3
Merge branch 'master' of https://github.com/NixOS/nixpkgs into new-package-frescobaldi