Revert "Return an error when the file couldn’t be successfully opened"

This prevent the buggy XBMC mythtv plugin to connect. As the module is popular, I'm making an exception.

But the issue will arise again in 0.28, so cmyth should just do the proper thing and test for errors

This reverts commit a451d38ea312d3f654f4efd16471bba3617756e1.