This triggers a Valgrind out-of-bounds read report. It was introduced by commit5d7849ad7f. No CHANGES entry necessary as it doesn't have any user-visible or behavioral change. It removes an out-of-bounds read issue that went undetected when allocated through isc_mem as the memory was present. The memory read was compared to itself, so it has no behavioral change. (cherry picked from commitffc393dd18)