--tc-heuristic-recover option values are broken due to option parser enumerating them starting from 0 and the source code enumerating them starting from 1:

sql/mysqld.c:

static const char *tc_heuristic_recover_names[]=

{

  "COMMIT", "ROLLBACK", NullS

};

sql/sql_class.h:

#define TC_HEURISTIC_RECOVER_COMMIT   1

#define TC_HEURISTIC_RECOVER_ROLLBACK 2

Percona has fixed this by adding "NONE" as first option, MySQL 5.7 by adding "OFF"