I did another reboot test to validate the error. It does exist; it does not spam munmap error like it did with the aptitude install.
I then marked the log file, shutdown (1 munmap during), marked it again and then started it (1 munmap during).
MARK PRE-SHUTDOWN
2016-10-11 20:02:45 UTC [1656-2] LOG: received fast shutdown request
2016-10-11 20:02:45 UTC [1656-3] LOG: aborting any active transactions
2016-10-11 20:02:45 UTC [1707-2] LOG: autovacuum launcher shutting down
2016-10-11 20:02:45 UTC [1704-1] LOG: shutting down
2016-10-11 20:02:45 UTC [1704-2] LOG: database system is shut down
2016-10-11 20:02:45 UTC [1656-4] LOG: munmap(0x7fff80000000) failed: Invalid argument
MARK PRE-START
2016-10-11 20:03:02 UTC [9894-1] LOG: database system was shut down at 2016-10-11 20:02:45 UTC
2016-10-11 20:03:02 UTC [9894-2] LOG: MultiXact member wraparound protections are now enabled
2016-10-11 20:03:02 UTC [9893-1] LOG: database system is ready to accept connections
2016-10-11 20:03:02 UTC [9898-1] LOG: autovacuum launcher started
2016-10-11 20:03:02 UTC [9899-1] LOG: munmap(0x7fff80000000) failed: Invalid argument
2016-10-11 20:03:02 UTC [9900-1] [unknown]@[unknown] LOG: incomplete startup packet