Previously, this would call 'expand-file-name' on the file name, but
that normalizes the value, turning something like "~/." into
"/home/user". As a result, Pcomplete didn't work for dotfiles after
"~/" (bug#28064).
* lisp/eshell/em-dirs.el (eshell-expand-user-reference): New
function...
(eshell-expand-user-reference): ... use it.