Steps to reproduce:

   emacs -Q
   M-x eshell-command RET oops C-g
   M-x eshell
   <up>

This will show the most-recent command in the Eshell history as "oops". 
That's because it was adding to the history in 'minibuffer-exit-hook', 
which runs regardless of *how* you exit the minibuffer. This regressed 
from 093a360251, and I misunderstood the conditions where 
'minibuffer-exit-hook' runs.

Attached is a patch to fix this. Is this ok for the release branch?