Noam Postavsky <npostavs@users.sourceforge.net> writes:

> A good start would be to step through eshell-pcomplete with edebug and
> find the piece of code which deletes the asterisk.

It's in `pcomplete-parse-arguments` (in pcomplete.el)
Line 776 on master:
```
      (when (and begin (not pcomplete-show-list))
	(delete-region begin (point))
	(pcomplete-insert-entry "" pcomplete-stub))
```

Hope that helps.