dl-5.alpinelinux.org repository is not updated anymore for month or so
APKINDEX (at least http://dl-5.alpinelinux.org/alpine/v3.6/main/x86\_64/APKINDEX.tar.gz) stopped updating on 2017-10-25
(from redmine: issue id 8198, created on 2017-11-24, closed on 2018-01-25)