Ticket #3124: really escape Zsh history

Per Zsh documentation last command prefixed with space lingers in the
internal history until the next command is entered before it vanishes.
To make it vanish right away, type a space and press return.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Merge branch '3124_zsh_escape_history'

* 3124_zsh_escape_history:
  Ticket #3124: really escape Zsh history