Changelog for ruby2.1-rubygem-pg-0-0.21.0-4.9.x86_64.rpm :

* Sat Jan 19 2019 Marcus Rueckert - rb_build_ruby_abi needs to be rb_build_ruby_abis
* Fri Jan 18 2019 Marcus Rueckert - use rb_build_ruby_abi instead of rb_default_ruby_abi
* Mon Aug 27 2018 Marcus Rueckert - provide 0.x branch too