Re: highlight failed part of isearch input

[Richard Stallman]

    I notice something that strikes me as perhaps a bug, but I don't know which
    behavior was intended by `C-M-w'. If you use `C-s abx C-a' in a buffer with
    only `abcd', and then you use `C-s C-s C-M-w', the search string is changed
    from `abx' to `ab', but the prompt/echo still says "Failing", which is not
    really correct. In fact, it has not yet searched again with the updated
    search string from `C-M-w' - you must hit `C-s' again to start the search
    (which does not fail).

Given that it doesn't search again, the prompt may not be a bug.
But the interface is definitely confusing.

Juri Linkov is the author of this command.
Juri, is there a reason it should work the way it does?