anchor.diff:  
     src = fetchurl {
       url = "https://www.kernel.org/pub/software/scm/git/git-${version}.tar.xz";
  -    sha256 = "09lzwa183nblr6l8ib35g2xrjf9wm9yhk3szfvyzkwivdv69c9r2";
  +    sha256 = "0s03ix9j1h0yychkh1l1cgpr1l9lwzn3rprl08rk8ii5ix02i0l8";
     };
   
     outputs = [ "out" ];
  
positive.code:       ln -s $out/libexec/git-core/git-http-backend $out/bin/git-http-backend
      '' + stdenv.lib.optionalString perlSupport ''
        # wrap perl commands
        makeWrapper "$out/share/git/contrib/credential/netrc/git-credential-netrc" $out/bin/git-credential-netrc \
                    --set PERL5LIB   "$out/${perlPackages.perl.libPrefix}:${perlPackages.makePerlPath perlLibs}"
        wrapProgram $out/libexec/git-core/git-cvsimport \
                    --set GITPERLLIB "$out/${perlPackages.perl.libPrefix}:${perlPackages.makePerlPath perlLibs}"
  
negative.code: assert svnSupport -> perlSupport;
  
  let
    version = "2.26.1";
    svn = subversionClient.override { perlBindings = perlSupport; };
  
    gitwebPerlLibs = with perlPackages; [ CGI HTMLParser CGIFast FCGI FCGIProcManager HTMLTagCloud ];
  