Window functions: assertion failure with empty OVER() clause

create table t40 (a int) engine=InnoDB;

select row_number() over () from t40;

mysqld: /src/10.2/sql/filesort.h:70: Filesort::Filesort(ORDER*, ha_rows, bool, SQL_SELECT*): Assertion `order' failed.

160521 19:13:05 [ERROR] mysqld got signal 6 ;

  Program received signal SIGABRT, Aborted.

  0x00007ffff5f90425 in __GI_raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64

  64	../nptl/sysdeps/unix/sysv/linux/raise.c: No such file or directory.

(gdb) wher

  #0  0x00007ffff5f90425 in __GI_raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64

  #1  0x00007ffff5f93b8b in __GI_abort () at abort.c:91

  #2  0x00007ffff5f890ee in __assert_fail_base (fmt=<optimized out>, assertion=0x5555563e45cb "order", file=0x5555563e4590 "/home/psergey/dev-git/10.2-window-funcs-r10/sql/filesort.h", line=<optimized out>, function=<optimized out>) at assert.c:94

  #3  0x00007ffff5f89192 in __GI___assert_fail (assertion=0x5555563e45cb "order", file=0x5555563e4590 "/home/psergey/dev-git/10.2-window-funcs-r10/sql/filesort.h", line=70, function=0x5555563e8940 "Filesort::Filesort(ORDER*, ha_rows, bool, SQL_SELECT*)") at assert.c:103

  #4  0x0000555555b01c16 in Filesort::Filesort (this=0x7fff5c013560, order_arg=0x0, limit_arg=18446744073709551615, sort_positions_arg=true, select_arg=0x0) at /home/psergey/dev-git/10.2-window-funcs-r10/sql/filesort.h:70

  #5  0x0000555555c2bcd8 in Window_funcs_sort::setup (this=0x7fff5c013518, thd=0x7fff5c000b00, sel=0x0, it=...) at /home/psergey/dev-git/10.2-window-funcs-r10/sql/sql_window.cc:1922

  #6  0x0000555555c2be0f in Window_funcs_computation::setup (this=0x7fff5c0134f8, thd=0x7fff5c000b00, window_funcs=0x7fff5c004fc8, tab=0x7fff5c0128a0) at /home/psergey/dev-git/10.2-window-funcs-r10/sql/sql_window.cc:1949

  #7  0x0000555555ac5573 in JOIN::make_aggr_tables_info (this=0x7fff5c011508) at /home/psergey/dev-git/10.2-window-funcs-r10/sql/sql_select.cc:2670

  #8  0x0000555555ac30b6 in JOIN::optimize_inner (this=0x7fff5c011508) at /home/psergey/dev-git/10.2-window-funcs-r10/sql/sql_select.cc:2068

  #9  0x0000555555abfc2c in JOIN::optimize (this=0x7fff5c011508) at /home/psergey/dev-git/10.2-window-funcs-r10/sql/sql_select.cc:1063

  #10 0x0000555555ac7ed0 in mysql_select (thd=0x7fff5c000b00, tables=0x7fff5c010e10, wild_num=0, fields=..., conds=0x0, og_num=0, order=0x0, group=0x0, having=0x0, proc_param=0x0, select_options=2147748608, result=0x7fff5c0114e8, unit=0x7fff5c004550, select_lex=0x7fff5c004c70) at /home/psergey/dev-git/10.2-window-funcs-r10/sql/sql_select.cc:3521

  Filesort(ORDER *order_arg, ha_rows limit_arg, bool sort_positions_arg,

           SQL_SELECT *select_arg):

    order(order_arg),

...

  {

    DBUG_ASSERT(order);

  };