rubygem-coveralls is a build requirement for rubygem-thread_safe
Fails to install on CentOS with: Error: Package: rubygem-coveralls-0.8.15-1.el7.noarch (temp) Requires: rubygem(tins) >= 1.6.0 Installing: rubygem-tins-1.0.0-2.el7.noarch (validated) rubygem(tins) = 1.0.0 Error: Package: rubygem-coveralls-0.8.15-1.el7.noarch (temp) Requires: rubygem(simplecov) >= 0.12.0 Installing: rubygem-simplecov-0.7.1-8.el7.noarch (validated) rubygem(simplecov) = 0.7.1 Error: Package: rubygem-coveralls-0.8.15-1.el7.noarch (temp) Requires: rubygem(json) >= 1.8 Installing: rubygem-json-1.7.7-29.el7.x86_64 (base) rubygem(json) = 1.7.7-29.el7