hg2git has been put into repo fast-export. make it work again

svn path=/nixpkgs/trunk/; revision=17977

pkgs/applications/version-management/git-and-tools/fast-export/default.nix

@@ -0,0 +1,35 @@
+args: with args;
+stdenv.mkDerivation {
+  name = "fast-export";
+
+  src = sourceByName "git_fast_export";
+
+  buildInputs =([mercurial.python mercurial makeWrapper subversion]);
+
+  buildPhase="true"; # skip svn for now
+
+  # TODO also support svn stuff
+  # moving .py files into lib directory so that you can't pick the wrong file from PATH.
+  # This requires redefining ROOT
+  installPhase = ''
+    sed -i "s@/usr/bin/env.*@$(type -p python)@" *.py
+    l=$out/libexec/git-fast-export
+    ensureDir $out/{bin,doc/git-fast-export} $l
+    mv *.txt $out/doc/git-fast-export
+    sed -i "s@ROOT=.*@ROOT=$l@" *.sh
+    mv *.sh $out/bin
+    mv *.py $l
+    for p in $out/bin/*.sh; do
+      wrapProgram $p \
+        --set PYTHONPATH "$(echo ${mercurial}/lib/python*/site-packages)" \
+        --prefix PATH : "$(dirname $(type -p python))":$l
+    done
+  '';
+
+  # usage: 
+  meta = {
+      description = "import svn, mercurial into git";
+      homepage = "http://repo.or.cz/w/fast-export.git";
+      license = "?"; # the .py file is GPLv2
+  };
+}