bug#50900: 27.2; Evaluating open-line with a negative argument changes the behavior of self-insert

[Rodrigo Morales <moralesrodrigo1100@gmail.com>]

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This is a response to the message of Lars. Apparently, we get the same
backtrace.

```
Debugger entered--Lisp error: (error "Negative repetition argument -1")
  self-insert-command(-1)
  newline(-1)
  open-line(-1)
  eval((open-line -1) t)
  eval-expression((open-line -1) nil nil 127)
  funcall-interactively(eval-expression (open-line -1) nil nil 127)
  call-interactively(eval-expression nil nil)
  command-execute(eval-expression)
```

This is what C-h f open-line RET shows

```
open-line is an interactive compiled Lisp function in ‘simple.el’.

It is bound to C-o, <insertline>.

(open-line N)

  Probably introduced at or before Emacs version 19.29.

Insert a newline and leave point before it.
If there is a fill prefix and/or a ‘left-margin’, insert them on
the new line if the line would have been blank.
With arg N, insert N newlines.
```

On Wed, 29 Sept 2021 at 15:38, Rodrigo Morales <moralesrodrigo1100@gmail.com>
wrote:

> > 5. (At this point, whenever you insert a character, the cursor is
> >    moved to the beginning of the line which makes it seem that you are
> >    typing from left to right.)
>
> Typo: "right-to-left" instead of "from left to right"
>

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