No altitude on some aircraft, but it exists

Occasionally I see some aircraft not reporting alt, seem to be older aircraft, however, a quick test of MalcolmRobbs fork, and it reports it! quick kills' and restarts between the two confirm Antirez's version not decoding it, but Malcolm's does, its also been over several aircraft, tested over several days, so not sure where Malcolms changes get this but obviously I report it as a bug since the "upstream" parent/master/actual code devs version, does not.

I execute both binaries identical : dump1090 --net --interactive --aggressive

Example, aircraft VH-LEM

_Antirez_

DF 17: ADS-B message.
Capability : 5 (Level 2+3+4 (DF0,4,5,11,20,21,24,code7 - is on airborne))
ICAO Address : 7c384c
Extended Squitter Type: 4
Extended Squitter Sub : 1
Extended Squitter Name: Aircraft Identification and Category
Aircraft Type : Aircraft Type A
Identification : LEM

DF 17: ADS-B message.
Capability : 5 (Level 2+3+4 (DF0,4,5,11,20,21,24,code7 - is on airborne))
ICAO Address : 7c384c
Extended Squitter Type: 11
Extended Squitter Sub : 0
Extended Squitter Name: Airborne Position (Baro Altitude)
F flag : even
T flag : non-UTC
Altitude : 0 feet
Latitude : 77568 (not decoded)
Longitude: 70581 (not decoded)

DF 0: Short Air-Air Surveillance.
Altitude : 0 feet
ICAO Address : 7c384c

_MalcolmRobb_

DF 17: ADS-B message.
Capability : 5 (Level 2+3+4 (DF0,4,5,11,20,21,24,code7 - is airborne))
ICAO Address : 7c384c
Extended Squitter Type: 4
Extended Squitter Sub : 1
Extended Squitter Name: Aircraft Identification and Category
Aircraft Type : A1
Identification : LEM

DF 17: ADS-B message.
Capability : 5 (Level 2+3+4 (DF0,4,5,11,20,21,24,code7 - is airborne))
ICAO Address : 7c384c
Extended Squitter Type: 11
Extended Squitter Sub : 0
Extended Squitter Name: Airborne Position (Baro Altitude)
F flag : even
T flag : non-UTC
Altitude : 10500 feet
Latitude : -26.449219
Longitude: 152.823970

DF 0: Short Air-Air Surveillance.
VS : Airborne
CC : 0
SL : 0
Altitude : 10500 feet
ICAO Address : 7c384c