Re: 23.0.60; M-x occur no longer uses previous regexp as default

[Richard Stallman]

    In Emacs 22, M-x occur uses the previous regexp as default when invoked
    a second time, so you could just press RET to look for it again.

I think we should consider that a bug and fix it.

      Now
    you have to use M-p to receive the previous regexp, if you forget that
    Emacs hangs and uses 100% CPU (interruptible with C-g, backtrace
    follows):

Maybe one of these functions should signal an error if the regexp arg
is "".