Homebrew blocked by Error: invalid attribute for formula 'homebrew/php/php70': version (nil)

Question

I've tried brew update and brew doctor, fixing all errors that have come up thus far, but I'm still getting this error anytime I try to update or remove php70:

Error: invalid attribute for formula 'homebrew/php/php70': version (nil) /usr/local/Homebrew/Library/Homebrew/formula.rb:252:in `validate_attributes!' /usr/local/Homebrew/Library/Homebrew/formula.rb:199:in `initialize' /usr/local/Homebrew/Library/Homebrew/formulary.rb:88:in `new' /usr/local/Homebrew/Library/Homebrew/formulary.rb:88:in `get_formula' /usr/local/Homebrew/Library/Homebrew/formulary.rb:275:in `factory' /usr/local/Homebrew/Library/Homebrew/extend/ARGV.rb:69:in `block in resolved_formulae' /usr/local/Homebrew/Library/Homebrew/extend/ARGV.rb:54:in `map' /usr/local/Homebrew/Library/Homebrew/extend/ARGV.rb:54:in `resolved_formulae' /usr/local/Homebrew/Library/Homebrew/cmd/reinstall.rb:13:in `reinstall' /usr/local/Homebrew/Library/Homebrew/brew.rb:95:in `<main>'

I've even tried rebuild as specified here (How to build php70-xdebug from master via Homebrew?) but it returns the same error. Does anyone know how to proceed beyond this?