bug#10669: More debugging

[Michael Welsh Duggan <md5i@md5i.com>]

Okay.  Here's what the infinite loop actually is:

The C function 'command_loop' calls 'top_level_1', which eventually
evals 'top-level', which is 'normal-top-level'.  'normal-top-level'
notes that 'command-line-processed' is t, calls (message "Back to top
level."), and then returns.

Back to 'command_loop, which then calls 'command_loop_2', which calls
command_loop_1', which calls 'read_key_sequence', which calls
'read_char'.

'read_char' eventually calls 'kbd_buffer_get_event' at keyboard.c:2797.
This ends up calling getchar(), since we are running as a daemon
(keyboard.c:3796).  This getchar() returns -1.  'read_char' returns this
-1.

'read_key_sequence' takes this -1, and sets its return value to 0
(keyboard.c:9373).

'command_loop_1' takes this 0, and returns nil (keyboard.c:1463).
'command_loop_2' returns nil on nil.

'command_loop' then continues in its loop, calling 'top_level_1' again,
followed by 'command_loop_2'.

-- 
Michael Welsh Duggan
(md5i@md5i.com)