Unexpectedly, a ZWNBSP (U+FEFF) received/echoed by the MacOS Terminal while in
the first column causes a subsequent cursor position report to indicate the 2nd
column as the current only. I suppose in some weird world a zero-width
character can can't as a column position. So if the cursor position has moved
less than 2 columns (not exactly 0 columns), then consider it a UTF-8 terminal.
Non-UTF-8 terminals normally move the cursor 3 columns when echoing a UTF-8
encoded ZWNBSP. So to summarize, when echoing a ZWNBSP:

- Non-UTF-8 terminals: moves 3 columns
- MacOS terminal: moves 1 columns
- Other UTF-8 terminals: moves 0 columns