Seems that 2.0.0-p645 and 2.1.6 had the wrong checksum.

share/ruby-build/2.0.0-p645

 install_package "openssl-1.0.1m" "https://www.openssl.org/source/openssl-1.0.1m.tar.gz#095f0b7b09116c0c5526422088058dc7e6e000aa14d22acca6a4e2babcdfef74" mac_openssl --if has_broken_mac_openssl
-install_package "ruby-2.0.0-p645" "http://cache.ruby-lang.org/pub/ruby/2.0/ruby-2.0.0-p645.tar.gz#2dcdcf9900cb923a16d3662d067bc8c801997ac3e4a774775e387e883b3683e9" standard verify_openssl
+install_package "ruby-2.0.0-p645" "http://cache.ruby-lang.org/pub/ruby/2.0/ruby-2.0.0-p645.tar.gz#5e9f8effffe97cba5ef0015feec6e1e5f3bacf6ace78cd1cdf72708cd71cf4ab" standard verify_openssl

share/ruby-build/2.1.6

 install_package "openssl-1.0.1m" "https://www.openssl.org/source/openssl-1.0.1m.tar.gz#095f0b7b09116c0c5526422088058dc7e6e000aa14d22acca6a4e2babcdfef74" mac_openssl --if has_broken_mac_openssl
-install_package "ruby-2.1.6" "http://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.6.tar.gz#7b5233be35a4a7fbd64923e42efb70b7bebd455d9d6f9d4001b3b3a6e0aa6ce9" ldflags_dirs standard verify_openssl
+install_package "ruby-2.1.6" "http://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.6.tar.gz#1e1362ae7427c91fa53dc9c05aee4ee200e2d7d8970a891c5bd76bee28d28be4" ldflags_dirs standard verify_openssl