the latest ruby build depends on openssl, which is currently openssl-1.1, but was linked against openssl-1.0.

this results in problems like:

# ldd /usr/lib/ruby/2.4.0/x86_64-linux/digest/sha1.so
        libcrypto.so.1.0.0 => not found

unless openssl-1.0 is installed explicitly alongside.

this blocks #1307, because the build depends on a working ruby.