This commit partial reverts beed39e46fa021dd1c133c2c8eaaa81b524e68c7.
For users whose local brew is at around 2015-06-02 to 2015-06-11,
running `brew update` will emit following error:
Error: undefined method 'full_version' for OS::Mac:Module
This is caused by the same bug described in Homebrew/homebrew#42553.
Let's use `MACOS_FULL_VERSION` for now to restore `brew update` compatibility
for these users.
TODO: revert this commit after core code and formulae separation.
This is the (partially) documented public API for Homebrew.
The main class you should look at is the {Formula} class (and classes linked from there). That's the class that's used to create Homebrew formulae (i.e. package descriptions). Assume anything else you stumble upon is private.