An odd glitch in autopkgtest - package has no install candidates

[Dimitri John Ledkov]

https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-bionic/bionic/s390x/n/nginx/20180417_130943_7f698@/log.gz

Is pointed out as an "odd" failure. haveged was not available, yet it should have been installable at all times and has not moved since artful.... hence "odd".

Reading the log, I can see that during test bed setup "bionic-proposed InRelease" is fetched, but not "bionic InRelease" seems odd to me, but probably a red herring.