Only directories are candidates for superenv bin

Library/Homebrew/extend/ENV.rb

@@ -4,7 +4,7 @@ require 'extend/ENV/std'
 require 'extend/ENV/super'
 
 def superenv?
-  Superenv.bin && Superenv.bin.directory? && ARGV.env != "std"
+  Superenv.bin && ARGV.env != "std"
 end
 
 module EnvActivation

Library/Homebrew/extend/ENV/super.rb

@@ -40,7 +40,7 @@ module Superenv
   end
 
   def self.bin
-    @bin ||= (HOMEBREW_REPOSITORY/"Library/ENV").children.reject{|d| d.basename.to_s > MacOS::Xcode.version }.max
+    @bin ||= (HOMEBREW_REPOSITORY/"Library/ENV").subdirs.reject { |d| d.basename.to_s > MacOS::Xcode.version }.max
   end
 
   def reset