bug#18285: Acknowledgement (24.3.92; A combination of `display' on text and `invisible' and `before/after-string' leads to the before/after string being displayed twice)

[Dmitry Gutov]

Clarification: this part -

  If I replace (make-overlay pt (point)) with (make-overlay (1- pt)
  (point)), the result it, expectedly...

- is only true when (> pt (point-min)), e.g. when we started at the end 
of a non-empty buffer.