• Fix newer Ruby releases compiling on Yosemite when apple-gcc42 is present Homebrew
• Fix apple-gcc42–powered builds (Ruby pre-1.9.3) on Yosemite
• Fix calculating SHA-256 checksums on OS X Leopard
• Fix Rubinius build when libyaml is present in Homebrew
• Work around Rubinius LLVM incompatibilities on Yosemite
• Enable Rubinius builds to re-use cached LLVM dependencies between builds
• Avoid endless recursion when Rubinius is installed over existing one
• Don't display duplicate definitions