ITS#9249 librewrite: fix malloc/free corruption
If substitution parsing fails, would attempt to free a mapping that hadn't been allocated yet.
Also, on failure, caller in saslauthz would attempt to free a rwinfo struct that hadn't been allocated.
If substitution parsing fails, would attempt to free a mapping that hadn't been allocated yet.
Also, on failure, caller in saslauthz would attempt to free a rwinfo struct that hadn't been allocated.