* Allow hooks like preBuild to be set both through shell functions and   variables.  This is so you don't have to write things like
* Allow hooks like preBuild to be set both through shell functions and
  variables.  This is so you don't have to write things like

    preBuild=preBuild
    preBuild() {
      bla
    }

svn path=/nixpkgs/branches/stdenv-updates/; revision=13941

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