Re: multiple queries to delete excess backup version w/ custom

[martin rudalics]

> You might want to implement the function that saves as a call to the
> function that merely marks for saving, followed by a call to to
> custom-save-all, rather than duplicate the code.

Good.  But the end of `custom-variable-save' reads as

    (custom-save-all)
    (custom-variable-state-set widget)
    (custom-redraw-magic widget)))

and I think I should still do the last two calls _after_ calling
`custom-save-all' - just in case the latter throws an error.