cloud-init package install is unreliable

[Adrian Bridgett]

Using 0.7.9-48-g1c795b9-0ubuntu1~16.04.1 and testing on two machines, I had a 50% failure rate when installing "sl" and "mutt" packages (just testing).

dpkg: error: dpkg status database is locked by another process

There's nothing else in cloud-init that'd be running dpkg so I suspect this is a race with e.g. an apt-get update running as part of a boot (nothing I've specifically asked for in other words).

I might try and work around this with aptdcon as per https://askubuntu.com/questions/132059/how-to-make-a-package-manager-wait-if-another-instance-of-apt-is-running (we build AMIs and this is when we add user-data to those AMIs so we can _ensure_ that aptdcon is installed before user-data).

However it looks like cloud-init and package: is unreliable in other cases.