anchor.diff:    ==================
   
       services.posgresql.extraPlugins = [ pkgs.postgis.v_1_5_1 ];
  +
  +    services.postgresql.extraPlugins = [ (pkgs.postgis.override { postgresql = pkgs.postgresql94; }).v_2_1_4 ];  # BM - 2015/01/01
   
       or if you want to install 1.5.x and 1.3.x at the same time (which works
       because the .sql and .so files have different names):
  
positive.code: args@{fetchurl, composableDerivation, stdenv, perl, libxml2, postgresql, geos, proj, flex, ...}:
  
    /*
  
  
negative.code:     name = "postgis-${version}";
  
      src = fetchurl {
        url = "http://postgis.refractions.net/download/postgis-${fix.fixed.version}.tar.gz";
        inherit (fix.fixed) sha256;
      };
  
  