Warn if no status after eof

Author: José Valim

lib/mix/lib/mix/shell.ex

@@ -89,18 +89,25 @@ defmodule Mix.Shell do
       end
 
     port = Port.open({:spawn, shell_command(command)},
-                     [:stream, :binary, :exit_status, :hide, :use_stdio, {:env, env}|args])
+                     [:stream, :binary, :exit_status, :hide, :use_stdio, :eof, {:env, env}|args])
 
-    do_cmd(port, callback)
+    do_cmd(port, command, callback)
   end
 
-  defp do_cmd(port, callback) do
+  defp do_cmd(port, command, callback) do
     receive do
       {^port, {:data, data}} ->
         callback.(data)
-        do_cmd(port, callback)
-      {^port, {:exit_status, status}} ->
-        status
+        do_cmd(port, command, callback)
+      {^port, :eof} ->
+        receive do
+          {^port, {:exit_status, status}} ->
+            status
+        after
+          5_000 ->
+            IO.puts :stderr, "warning: did not receive exit status after command: #{command}"
+            0
+        end
     end
   end
 
@@ -126,6 +133,8 @@ defmodule Mix.Shell do
 
   defp validate_env(enum) do
     Enum.map enum, fn
+      {k, nil} ->
+        {String.to_char_list(k), false}
       {k, v} ->
         {String.to_char_list(k), String.to_char_list(v)}
       other ->