BUG: long prompts tangle ZLE

[Phil Pennock <phil@xxxxxxxxxxxxxxxxxxxxx>]

With both stock 3.1.5 and 3.1.5-patched(17 Nov) I am experiencing
strange behaviour with very long prompts.

If the prompt length is 80 characters (on an 80-char width term) then
 (a) the last character is not printed, or at least overwritten with a
     space;
 (b) more seriously, typing a command does not scroll the line up, but
     instead overwrites the start of the line.

Anything longer or shorter does not affect this.

I know, my prompt is too long.  I'm about to change my PS1 to only list
the last 30ish chars of %~.  And I haven't looked into this -- no WAY do
I know zsh's internals well enough to tinker in ZLE.

HTH
-- 
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