Re: suggestion in query-replace is messed up after cancelation

[Richard Stallman]

    Removing from-element from the history list is not a good solution.
    Most often I type C-g in the to-element prompt, when instead
    of typing a long to-element I need to switch to another buffer
    and copy to-element from that buffer (to yank it later from the kill ring
    to the to-element prompt).  After that I type M-% again, and definitely
    don't want to re-type the from-element.

So how about adding an empty to-string as a way to preserve parity?