gdb 'set confirm off' ignores missing source files

[Dan Grayson]

'set confirm off' ignores missing source files, surprisingly not issuing an
error message.  Here is an example:
-----------------------------------------------------------------------------
    cesium% gdb -nx
    "TERMCAP", line 1, col 1, terminal 'emacs': Missing separator
    GNU gdb 5.3-20021014 (Apple version gdb-250) (Sat Dec  7 02:14:27 GMT 2002)
    Copyright 2002 Free Software Foundation, Inc.
    GDB is free software, covered by the GNU General Public License, and you are
    welcome to change it and/or distribute copies of it under certain 
conditions.
    Type "show copying" to see the conditions.
    There is absolutely no warranty for GDB.  Type "show warranty" for details.
    This GDB was configured as "powerpc-apple-macos10".
    "TERMCAP", line 1, col 1, terminal 'emacs': Missing separator
    (gdb) source foobar
    foobar: No such file or directory.
    (gdb) set confirm off
    (gdb) source foobar
    (gdb) quit
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It seems to be undocumented.  From the info page:
-----------------------------------------------------------------------------
   By default, GDB is cautious, and asks what sometimes seems to be a
lot of stupid questions to confirm certain commands.  For example, if
you try to run a program which is already running:

     (gdb) run
     The program being debugged has been started already.
     Start it from the beginning? (y or n)

   If you are willing to unflinchingly face the consequences of your own
commands, you can disable this "feature":

`set confirm off'
     Disables confirmation requests.

`set confirm on'
     Enables confirmation requests (the default).

`show confirm'
     Displays state of confirmation requests.