bug#1337: crash on going into non-existing dir with find-file

[xah lee <xah@xahlee.org>]

  using a
This causes a hard crash.

Steps:

1. eval (find-file "file:///Users/xah/web/emacs/apple_pc_kb_diff.html")
then you'll go into a empty buffer.

2. now M-x find-file, hit Enter. Now i expect to go to the dir this  
file is located. (note that the file doesn't exist yet)

3. emacs crashed.

am pretty sure this is 100% reproducible. It crashed 3 times on me.

The problem occured because i was trying to open a local file, where  
the file path happend to be a url scheme path. Apparently, find-file  
does not recognize url scheme local files, but find-file-at-point  
auto launch browser when the file is url scheme. In any case, i got  
confused a bit because i know the file exist but i got a empty  
buffer. So i tried to go into th dir to see where exactly emacs think  
is the path, then crash.

In GNU Emacs 22.2.1 (powerpc-apple-darwin8.11.0, Carbon Version 1.6.0)
  of 2008-04-05 on g5.tokyo.stp.isas.jaxa.jp
Windowing system distributor `Apple Inc.', version 10.4.11
configured using `configure  '--prefix=/Applications/Emacs.app/ 
Contents/Resources' '--with-carbon' '--without-x' '--libexecdir=/ 
Volumes/Emacs/Emacs.app/Contents/MacOS/libexec' 'CFLAGS=-Os -arch  
i386 -arch ppc -isysroot /Developer/SDKs/MacOSX10.4u.sdk -DUSE_ATSUI - 
DUSE_MAC_TSM''

   Xah
∑ http://xahlee.org/

☄