html2haml (1.0.1)
installs dependancy haml (4.1.0.alpha.2)
https://github.com/haml/html2haml/blob/b15d7a13228f3d36f4102a7e72ab489b89af2080/html2haml.gemspec#L21
gem.add_dependency 'haml', '>= 4.0.0.rc.1'
html2haml (2.0.0.beta.1)
installs dependancy haml (4.0.4)
https://github.com/haml/html2haml/blob/2ba620b1bc63fa8c0399580bc86afc794b1ee28b/html2haml.gemspec#L23
gem.add_dependency 'haml', '~> 4.0.0'