* nixos-checkout: add an argument to specify the directory where the

sources should be stored.  E.g. "nixos-checkout /home/eelco/srcs"
  will check out to /home/eelco/srcs/{nixos,nixpkgs}.  Probably the
  /etc/nixos default should be removed eventually because /etc is a
  pretty weird place to keep large source trees.

svn path=/nixos/trunk/; revision=34086

modules/installer/tools/nixos-checkout.nix

@@ -14,7 +14,12 @@ let
     isExecutable = true;
     src = pkgs.writeScript "nixos-checkout"
       ''
-        cd /etc/nixos
+        #! ${pkgs.stdenv.shell} -e
+        
+        prefix="$1"
+        if [ -z "$prefix" ]; then prefix=/etc/nixos; fi
+        mkdir -p "$prefix"
+        cd "$prefix"
 
         # Move any old nixos or nixpkgs directories out of the way.
         backupTimestamp=$(date "+%Y%m%d%H%M%S")