igrigorik/em-synchrony — comment on commit b7d4ce32f3083139140cfcfd40e9b1bf23e0e4e2
File: em-synchrony.gemspec line 16
By lgierth:

eventmachine-0.12.10 has been released 2 1/2 years ago, I remember encountering some weirdness when using it with EM::Synchrony.