From 97c12b4bbfa5a4e2d4ff0a1e59788b12503a698c Mon Sep 17 00:00:00 2001
From: Andrew Janke <andrew@apjanke.net>
Date: Fri, 15 Jun 2018 20:07:02 -0400
Subject: [PATCH] brew audit: avoid error on head-only formulae

---
 Library/Homebrew/dev-cmd/audit.rb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Library/Homebrew/dev-cmd/audit.rb b/Library/Homebrew/dev-cmd/audit.rb
index 056d00863f..be8dfef9b3 100644
--- a/Library/Homebrew/dev-cmd/audit.rb
+++ b/Library/Homebrew/dev-cmd/audit.rb
@@ -584,6 +584,7 @@ module Homebrew
       ]
 
       throttled.each_slice(2).to_a.map do |a, b|
+        next if formula.stable.nil?
         version = formula.stable.version.to_s.split(".").last.to_i
         if @strict && a.include?(formula.name) && version.modulo(b.to_i).nonzero?
           problem "should only be updated every #{b} releases on multiples of #{b}"