a select command invalid selection variable name is now a fatal error in posix mode; many test suite additions

builtins/command.def

@@ -124,6 +124,10 @@ command_builtin (WORD_LIST *list)
 
 #define COMMAND_BUILTIN_FLAGS (CMD_NO_FUNCTIONS | CMD_INHIBIT_EXPANSION | CMD_COMMAND_BUILTIN | (use_standard_path ? CMD_STDPATH : 0))
 
+  /* This code isn't executed any more; look at execute_cmd.c:execute_simple_command()
+     where command is treated as a pseudo-reserved prefix so we can optimize
+     away forks where possible. */
+
   /* We don't want this to be reparsed (consider command echo 'foo &'), so
      just make a simple_command structure and call execute_command with it. */
   command = make_bare_simple_command (line_number);
@@ -134,8 +138,8 @@ command_builtin (WORD_LIST *list)
 
   add_unwind_protect (uw_dispose_command, command);
   result = execute_command (command);
+  dispose_command (command);
 
-  run_unwind_frame ("command_builtin");
-
+  discard_unwind_frame ("command_builtin");
   return (result);
 }