Problem with dbstep

[John Swensen]

First, I have to say that being able to step a line at a time is  
awesome.  However, Octave crashes when you try to dbstep past the end  
of a file.

test.m
--------
function a = test(b)

a=1*b;
a = 2*b;
a=3*b;


octave:1> dbstop('test',3);
octave:2> a=test(1)
debug> dbstep
<segfault occurs>

Here is the backtrace:
#0  0xb7a56534 in tree_statement::line (this=0x8313a60) at pt-stmt.cc:60
#1  0xb77bb63f in octave_call_stack::do_current_line (this=0xb7fb283c)  
at toplev.cc:103
#2  0xb763bd5d in get_debug_input (prompt=@0xbfb65530) at toplev.h:125
#3  0xb763c7ce in do_keyboard (args=@0xbfb6564c) at input.cc:866
#4  0xb7a2a7ed in tree_identifier::rvalue (this=0x81aec38, nargout=1)  
at pt-id.cc:60
#5  0xb7a2a059 in tree_identifier::rvalue (this=0x81aec38) at pt-id.cc: 
109
#6  0xb7a5091f in tree_parameter_list::convert_to_const_vector  
(this=0x841de40, varargout=@0xbfb658b8)
     at pt-decl.h:68
#7  0xb78ee9ea in octave_user_function::do_multi_index_op  
(this=0x810d468, nargout=1, args=@0x8220ea0)
     at ov-usr-fcn.cc:510
#8  0xb78ef654 in octave_user_function::subsref (this=0x810d468,  
type=@0x820a4cc, idx=@0xbfb65b9c,
     nargout=1) at ov-usr-fcn.cc:337
#9  0xb78f0775 in octave_user_function::subsref (this=0x810d468,  
type=@0x820a4cc, idx=@0xbfb65b9c)
     at ov-usr-fcn.h:287
#10 0xb7888e32 in octave_value::subsref (this=0xbfb65bc4,  
type=@0x820a4cc, idx=@0xbfb65b9c, nargout=1)
     at ov.cc:1036
#11 0xb7a3157b in tree_index_expression::rvalue (this=0x820a4a8,  
nargout=1) at pt-idx.cc:385
#12 0xb7a2e7e9 in tree_index_expression::rvalue (this=0x820a4a8) at pt- 
idx.cc:396
#13 0xb7a12df1 in tree_simple_assignment::rvalue (this=0x8215e60) at  
pt-assign.cc:202
#14 0xb7a11c00 in tree_simple_assignment::rvalue (this=0x8215e60,  
nargout=0) at pt-assign.cc:184
#15 0xb7a57281 in tree_statement::eval (this=0x8215e90, silent=false,  
nargout=0,
     in_function_or_script_body=false) at pt-stmt.cc:124
#16 0xb7a57953 in tree_statement_list::eval (this=0x84346a0,  
silent=true, nargout=0) at pt-stmt.cc:186
#17 0xb77c158f in main_loop () at toplev.cc:425
#18 0xb7746667 in octave_main (argc=1, argv=0xbfb66134, embedded=0) at  
octave.cc:852
#19 0x0804878a in main (argc=136088760, argv=0x635f6873) at main.c:35

John Swensen