Need to reset the POSTDISPLAY if exiting early

Specific case where this matters is following:

Be in vi insert mode with some text in the buffer and the cursor at the
end of the buffer. Press `esc` to trigger `vi-cmd-mode widget`, then
before the cursor moves (KEYTIMEOUT), press `h` to trigger
`vi-backward-char` widget. When `vi-cmd-mode` original widget exits,
KEYS_QUEUED_COUNT will be non-zero and the suggestion will be lost.

src/widgets.zsh

@@ -55,6 +55,7 @@ _zsh_autosuggest_modify() {
 
 	# Don't fetch a new suggestion if there's more input to be read immediately
 	if (( $PENDING > 0 )) || (( $KEYS_QUEUED_COUNT > 0 )); then
+		POSTDISPLAY="$orig_postdisplay"
 		return $retval
 	fi