fix for the shell arg handling issues

The setup-env.sh script now saves off the argument array before shifting off
all the arguments so that the final command invocation doesn't arbitrarily
requote the arguments.  All external quoting is preserved now.  This has been
thoroughly tested with zsh, but should probably be tested with bash etc.
before acceptance.

share/spack/setup-env.sh

@@ -56,6 +56,12 @@
 # spack dotfiles.
 ########################################################################
 function spack {
+    # save raw arguments into an array before butchering them
+    args=()
+    for a in "$@"; do
+        # yup, this is awful, blame bash2 compat
+        args=("${args[@]}" "$a")
+    done
     # accumulate initial flags for main spack command
     _sp_flags=""
     while [[ "$1" =~ ^- ]]; do
@@ -116,7 +122,7 @@ function spack {
             esac
             ;;
         *)
-            command spack $_sp_flags $_sp_subcommand $_sp_spec
+            command spack "${args[@]}"
             ;;
     esac
 }