From 91ccd8435c6f19e9937b6aff5946e86f1eb63c05 Mon Sep 17 00:00:00 2001
From: aereal <aereal@aereal.org>
Date: Thu, 13 Nov 2014 22:56:31 +0900
Subject: [PATCH] Regard any installation of the formula as conflicts

Closes Homebrew/homebrew#34159.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
---
 Library/Homebrew/formula_installer.rb | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index 23813c3e67..fe3a00fd2c 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -201,9 +201,9 @@ class FormulaInstaller
   def check_conflicts
     return if ARGV.force?
 
-    conflicts = formula.conflicts.reject do |c|
-      keg = Formulary.factory(c.name).prefix
-      not keg.directory? && Keg.new(keg).linked?
+    conflicts = formula.conflicts.select do |c|
+      formula = Formulary.factory(c.name)
+      formula.linked_keg.exist? && formula.opt_prefix.exist?
     end
 
     raise FormulaConflictError.new(formula, conflicts) unless conflicts.empty?