What is the meaning of “All rights reserved” next to a permissive license?

Question

Suppose that you're trying to fork a software package, which mentions in its manifest that it is distributed under the "MIT" license:

[..]
License:             MIT
Copyright:           JC Holder
License-file:        LICENSE
[..]

However, upon inspection of the license file, you find this (followed by the Expat license text):

Copyright (c) 1970, JC Holder
All rights reserved.

The MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy [..]

How should this be interpreted? My interpretation of the conditions of the Expat license

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

is that only the Copyright line and the text starting with Permission (not necessarily including the warranty disclaimer) shall be included in copies of the Software.

Answer 1

Wikipedia says this:

"All rights reserved" is a phrase that originated in copyright law as a formal requirement for copyright notice. It indicates that the copyright holder reserves, or holds for their own use, all the rights provided by copyright law under one specific copyright treaty.

That's what it means in this context.

Now according to Wikipedia (again) the "All rights reserved" phrase is not required in a copyright notice, and the previous article explains that the it has been obsolete since 2000 when Nicaragua signed the Berne Convention. Thus, it makes no difference if you include those words from the perspective of Copyright Law.

But why quibble about it? If the copyright holder (or license designer) has included the "All rights reserved" phrase, they presumably thought it was necessary. I would have said it was polite to respect their opinion on this, and include the "All rights reserved" phrase when you copy their code. Wouldn't you?