merge revision(s) bb849ffdb18305f01457de4e9848c830eb83a2d7:
Added explicitly begin-end block for Ruby 2.4. strscan, ipaddr and some default gems still support Ruby 2.4. After this, I extract this CoreAssertions to their repositories.
merge revision(s) bb849ffdb18305f01457de4e9848c830eb83a2d7: