When InnoDB compares varchar field in ucs2 with given key using bin collation,
it calls my_strnncollsp_ucs2_bin() to perform comparison.
Because field length was lesser than length of key field should be padded
with trailing spaces in order to get correct result. 
Because  my_strnncollsp_ucs2_bin() was calling my_strnncollp_ucs2_bin(), which
doesn't pads field, wrong comparison result was returned. This results in
wrong result set.

my_strnncollsp_ucs2_bin() now compares fields like my_strnncollsp_ucs2 do,
but using binary collation.