Bug#21188 mysqlimport returns random exit code

 - Only handle return codes from 'pclose' greater than zero as errors.
 - It appears pclose can return -1 with errno set to ECHILD although the executin
process completed successfully. 


client/mysqltest.c:
  Only handle return codes from 'pclose' greater than zero as errors.

client/mysqltest.c

@@ -1207,7 +1207,7 @@ static void do_exec(struct st_query *query)
     }
   }
   error= pclose(res_file);
-  if (error != 0)
+  if (error > 0)
   {
     uint status= WEXITSTATUS(error), i;
     my_bool ok= 0;