fix errors

Author: greg-rychlewski

lib/ecto/adapters/myxql.ex

@@ -550,6 +550,7 @@ defmodule Ecto.Adapters.MyXQL do
     end
 
     {args, cmd_opts} = args_cmd_opts(opts, opt_args, cmd_opts)
+    cmd = String.to_charlist(command)
 
     cmd =
       if Path.type(cmd) == :absolute do
@@ -558,7 +559,7 @@ defmodule Ecto.Adapters.MyXQL do
         :os.find_executable(cmd) || :erlang.error(:enoent, [cmd, args, cmd_opts])
       end
 
-    port_opts = port_opts(cmd_opts, [args: args])
+    port_opts = port_opts(cmd_opts, args: args)
     port = Port.open({:spawn_executable, cmd}, port_opts)
     Port.command(port, contents)