Without this change, a phantom space appears after any character with
default emoji presentation that is converted to text with VS15. The only
other terminal I know of that respects variation selectors is Kitty, and
it walks the cursor back, which feels like the best choice, since that
way the behavior is observable (no way to know if the terminal supports
variation selectors otherwise without hard-coding that info per term)
and "dumb" programs like `cat` will output things correctly, and not
gain a phantom space after any VS15'd emoji.
fdd22ec786