autobuild, CI broken by unix epoch > 1700000000

[Douglas Bagnall]

To get a unique OID in a test, we have

governs_id = f'1.3.6.1.4.1.7165.4.6.2.9.{self.timestamp[-8:]}.{suffix}'

which would have been fine for most of the last 90000000 seconds, but it 
turns out that an OID field can't start with zero.

Today at 11:13:20 NZ time the epoch flipped over to 1700000000, which 
means `self.timestamp[-8:]` now starts with a number of zeros.

We will need to backport to 4.19.

Douglas