[REG 5.6.0 -> 5.6.1] QHostAddress behaviour for "31c3" changed

In 5.6.0, "31c3" is invalid:

>>> qVersion()
'5.6.0'
>>> QHostAddress('31c3').isNull()
False

While in 5.6.1 it suddenly is valid:

>>> qVersion()
'5.6.1'
>>> QHostAddress('31c3').isNull()
True

The qhostaddress source files didn't change since months, so I wonder if this was an intended change?

(examples using PyQt, but that shouldn't make any difference)