Assertion:

mysqld: item_cmpfunc.cc:846: longlong get_datetime_value(THD*, Item**, Item, Item, bool*): Assertion `item->null_value' failed.

backtrace:
#8 0x006b0d98 in __assert_fail () from /lib/libc.so.6
#9 0x081e32d8 in get_datetime_value (thd=0x9c67090, item_arg=0xb6b04d94, cache_arg=0xb6b04dbc, warn_item=0xb6b0b7b0, is_null=0xb6e37b1e)
at item_cmpfunc.cc:846
#10 0x081e36df in Arg_comparator::compare_datetime (this=0xb6b04d90) at item_cmpfunc.cc:957
#11 0x081ca14c in Arg_comparator::compare (this=0xb6b04d90) at item_cmpfunc.h:71
#12 0x081e5231 in Item_func_eq::val_int (this=0xb6b04d18) at item_cmpfunc.cc:1657
#13 0x082e34fa in make_join_select (join=0xb6b04e78, select=0xb6b0b6a8, cond=0xb6b04d18) at sql_select.cc:6272
#14 0x082d5306 in JOIN::optimize (this=0xb6b04e78) at sql_select.cc:1147
#15 0x082d9ebd in mysql_select (thd=0x9c67090, rref_pointer_array=0x9c68570, tables=0xb6b047c8, wild_num=1, fields=..., conds=0xb6b04d18, og_num=0,
order=0x0, group=0x0, having=0x0, proc_param=0x0, select_options=2147764736, result=0xb6b04e60, unit=0x9c68208, select_lex=0x9c68478)
at sql_select.cc:2530
#16 0x082d292e in handle_select (thd=0x9c67090, lex=0x9c681ac, result=0xb6b04e60, setup_tables_done_option=0) at sql_select.cc:269
#17 0x0827aa6f in execute_sqlcom_select (thd=0x9c67090, all_tables=0xb6b047c8) at sql_parse.cc:5129
#18 0x08271926 in mysql_execute_command (thd=0x9c67090) at sql_parse.cc:2278
#19 0x0827cc28 in mysql_parse (thd=0x9c67090, rawbuf=0xb6b04628 "SELECT * FROM t1 WHERE f1 IN ( COALESCE( f1 , MAKEDATE( 2014 , 123 ) ) )", length=73,
found_semicolon=0xb6e39210) at sql_parse.cc:6054
#20 0x0826f580 in dispatch_command (command=COM_QUERY, thd=0x9c67090,
packet=0x9cac539 "SELECT * FROM t1 WHERE f1 IN ( COALESCE( f1 , MAKEDATE( 2014 , 123 ) ) ) ", packet_length=74) at sql_parse.cc:1249
#21 0x0826e7b0 in do_command (thd=0x9c67090) at sql_parse.cc:889
#22 0x0826caf5 in handle_one_connection (arg=0x9c67090) at sql_connect.cc:1136
#23 0x00116919 in start_thread () from /lib/libpthread.so.0
#24 0x0076acce in clone () from /lib/libc.so.6

test case:

CREATE TABLE t1 ( f1 time ) ;
INSERT INTO t1 VALUES ('21:43:24');
SELECT * FROM t1 WHERE f1 IN ( COALESCE( f1 , MAKEDATE( 2014 , 123 ) ) ) ;