From e63d490874dd57d363643e49d6a7ce8fe17818d2 Mon Sep 17 00:00:00 2001
From: Mike McQuaid <mike@mikemcquaid.com>
Date: Tue, 17 Jul 2018 14:59:50 +0100
Subject: [PATCH] formula: handle unavailable missing formulae.

Fixes #4494.
---
 Library/Homebrew/formula.rb | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index 10b483562c..8cd37083b4 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -1557,6 +1557,10 @@ class Formula
     runtime_formula_dependencies.select do |f|
       hide.include?(f.name) || f.installed_prefixes.empty?
     end
+  # If we're still getting unavailable formulae at this stage the best we can
+  # do is just return no results.
+  rescue FormulaUnavailableError
+    []
   end
 
   # @private