assertion fails

[Tak Ota]

Today's CVS code fails assertion at line 19773 in xdisp.c when info is
invoked.  it->descent being -1 is the problem.  Following is the call
stack.

-Tak

x_produce_glyphs(it * 0x0082ecc8) line 19773 + 29 bytes
display_line(it * 0x0082ecc8) line 14939 + 22 bytes
try_window(int -2125923840, text_pos {...}) line 12545 + 12 bytes
redisplay_window(int -2125923840, int 0) line 12310 + 17 bytes
redisplay_window_0(int -2125923840) line 10851 + 11 bytes
internal_condition_case_1(int (void)* 0x010805ab redisplay_window_0(int), int 
-2125923840, int -1590098736, int (void)* 0x0108058a 
redisplay_window_error(void)) line 1426 + 7 bytes
redisplay_windows(int -2125923840) line 10832 + 25 bytes
redisplay_internal(int 1) line 10412 + 15 bytes
redisplay_preserve_echo_area(int 2) line 10637 + 7 bytes
sit_for(int 2, int 0, int 0, int 1, int 1) line 6358 + 7 bytes
Fsit_for(int 2, int 0, int 557336576) line 6421 + 45 bytes
Fexecute_extended_command(int 557336576) line 9814 + 28 bytes
Ffuncall(int 2, int * 0x0082fa98) line 2780 + 17 bytes
Fcall_interactively(int 557415520, int 557336576, int -2127049728) line 877 + 
19 bytes
Fcommand_execute(int 557415520, int 557336576, int 557336576, int 557336576) 
line 9697 + 17 bytes
command_loop_1() line 1792 + 31 bytes
internal_condition_case(int (void)* 0x01014969 command_loop_1(void), int 
557414000, int (void)* 0x010144e3 cmd_error(void)) line 1385 + 3 bytes
command_loop_2() line 1319 + 21 bytes
internal_catch(int 557410264, int (void)* 0x010147de command_loop_2(void), int 
557336576) line 1144 + 7 bytes
command_loop() line 1298 + 23 bytes
recursive_edit_1() line 991 + 5 bytes
Frecursive_edit() line 1053
main() line 1768
EMACS! mainCRTStartup + 180 bytes
_start() line 131