Varnish 2.1.5 Assert Error

[Joseph Begumisa]

Anyone have an idea what the panic message below means? I've looked at
the list archives and tickets and the closest issue that I could find
was a defect whereby a  long string overflowing obj.ws.  I'm not too
sure that is what is happening here but if it helps the url in the
"err_reason" below that I have shortened was actually 300 characters
long.  Any help would be appreciated.  Thanks.

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Apr 19 22:54:16 cache013 Y.Y.Y[4368]: child (28917) Started
Apr 19 22:54:16 cache013 Y.Y.Y[4368]: Child (28917) said
Apr 19 22:54:16 cache013 Y.Y.Y[4368]: Child (28917) said Child starts
Apr 19 22:54:20 cache013 Y.Y.Y[4368]: Child (28917) died signal=6
Apr 19 22:54:20 cache013 Y.Y.Y[4368]: Child (28917)

Panic message: Assert error in WS_Release(), cache_ws.c line 193:
Condition(bytes <= ws->e - ws->f) not true.
thread = (cache-worker)
ident = Linux,2.6.18-164.11.1.el5,x86_64,-smalloc,-hclassic,epoll
Backtrace:
	0x423f86: pan_ic+b6
	0x42f105: WS_Release+f5
	0x4294b6: vrt_assemble_string+f6
	0x42d8d5: VRT_SetHdr+f5
	0x2aaaac503ee0: _end+2aaaabe90358
	0x428846: VCL_error_method+46
	0x4137d9: cnt_error+159
	0x414271: CNT_Session+321
	0x426378: wrk_do_cnt_sess+b8
	0x42567e: wrk_thread_real+32e sp = 0x2aac6e302008 {   fd = 161, id =
161, xid = 1694570931,   client = X.X.X.X 51048,   step = STP_ERROR,
handling = deliver,   err_code = 750, err_reason = /a/b.html

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Regards,

Joseph