No way to inhibit default filename merge on C-X C-F

[Stephen Robbins <STEVER@MIT-REAGAN>]

In Symbolics 3600 ZWEI in Release 6.0, IP-TCP 29.0, AISite 9.5,
microcode TMC5-MIC 319, FEP 18, Rodent Free Namespace Editor, on Lisp Machine Apiary-8:

I wanted to find a file on a Berkeley 4.2 UNIX.  I did not know
the full pathname of the file, so I used the leading ~ character
(~<username> is the same as the pathname of the home directory
of <username>) convention.

I did C-X C-F

SPEAKER:~stever/.int_cshrc

The Lisp Machine merged this with my default,
AP6:>Stever>actors>file.lisp, to produce:

SPEAKER:/Stever/actors/~stever/.int_cshrc

It would be nice to let Find File take an argument to inhibit pathname
merging.

                Stever