.dir-locals/automount

[HASM]

In my machine I have two automount points:
  /net -hosts
which allows me to go to
  /net/host/path/to/remote/file/on/host
and
  /smb (complicated automount map)
which allows me to to go
  /smb/windows_host/share/path/to/file/on/windows_host/share
the "complicated automount map" makes
  /smb/windows_host
another mount point of type autofs

In emacs 24.4.1 when I open
  /net/host/path/to/remote/file/on/host
things seem to work fine, when I try to open
  /smb/windows_host/share/path/to/file/on/windows_host/share
I get this error:
  Error reading dir-locals: (file-error "Read error" "is a directory" 
"/smb/.dir-locals.el")
Note that until first (auto)mount, neither /smb/windows_host nor
/smb/windows_host/share, exist on the system.

Setting the obsolete variable automount-dir-prefix as
  (setq automount-dir-prefix "^/smb/")
makes no difference.
Setting its replacement
  (setq directory-abbrev-alist '(("^/smb/" . "/"))
makes the opening fail.

What is the workaround for this?  (Works fine on xemacs ...)

-- HASM