bug#18951: 24.4.51; eshell-pcomplete removes asterisk when attempting completion

[Dmitry Gutov]

1. Open a new Eshell session.
2. Type `*'.
3. Press `TAB' (invoking `eshell-pcomplete'), or `M-x pcomplete', or
   `M-x completion-at-point'.
4. See the asterisk removed as the completions buffer is displayed.

I don't think it makes much sense (just replace it when a completion is
inserted), and it's quite inconvenient when
`pcomplete-completions-at-point' is used from company-mode during idle
completion, as reported here:
https://github.com/company-mode/company-mode/issues/218

In GNU Emacs 24.4.51.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8)
 of 2014-11-03 on axl
Repository revision: 117658 
michael.albinus@gmx.de-20141102112256-548dk6al63uy76uh
Windowing system distributor `The X.Org Foundation', version 11.0.11501000
System Description:     Ubuntu 14.04.1 LTS