bug#15372: eshell gives environment variables high precedence

[Glenn Morris]

Package: emacs
Version: 24.3

I don't use eshell, so maybe this is how it is supposed to work, but
from the point of view of normal shells, this seems wrong:

foo=FOOBAR emacs -Q -f eshell
eshell> for foo in 5 { echo $foo }
        -> FOOBAR

Cf:

bash> export foo=FOOBAR
bash> for foo in 5; do echo $foo; done
      -> 5