This bug was caused by unitialized value that was the result of a bad 5.0 merge.
sql/sql_class.h:
Readded comments lost in a bad merge.
sql/sql_insert.cc:
Fixed code to completely initialize (zero) the "COPY_INFO info" var in the same manner as the delayed write code.
Readded a change that was lost in a bad merge.
tests/mysql_client_test.c:
Test case added for bug#29692.