M-x shell complete only executables in position 1

[Dan Jacobson]

In M-x shell,
$ ls -og
-r--r--r-- 1 1209 2006-11-30 07:09 wik-1164841782
-rwxr-xr-x 1 1224 2006-11-30 07:24 wik-1164842668
$ ./wik-116484<TAB> gives both as possible completions, whereas if
this were bash doing the thinking, it would know only to complete the
file with the executable bit set, in this situation.

Actually instead of fixing this, M-x shell should some how be unified
with bash or readline or something. No I don't want to use M-x
terminal-emulator or whatever. P.S., my favorite use of M-x shell is
for ssh some.host.org. So I can send lines at a time instead of
characters, etc.  Anyway, the above bug is on localhost, so M-x shell
has no excuses here.