Hi, yesterday i re enabled puppet on gerrit-test3 (after weeks of it being disabled to test a multi master gerrit setup) i noticed that apt-upgrade wanted to downgrade some python3 packages but also wanted to remove the 4.9 kernel so i cancelled the removal of the removal of the 4.9 kernel. But it downgraded the packages. Today i decided to upgrade to stretch watching out for the removal of the 4.9 kernel. It removed the kernel (i accidentally pressed no when i should have press yes to abort the removal). This broke gerrit-test3 so i have now rebuilt this as gerrit-test5.
openstack-mitaka-jessie appears related as the kernel removal only happened after that source was added.