info: sort HEAD keys by install date

This makes a lot more sense than sorting alphabetically by commit hash,
the previous behaviour.

Library/Homebrew/cmd/info.rb

@@ -137,7 +137,12 @@ module Homebrew
       EOS
     end
 
-    kegs = f.installed_kegs.sort_by(&:version)
+    kegs = f.installed_kegs
+    heads, versioned = kegs.partition { |k| k.version.head? }
+    kegs = [
+      *heads.sort_by { |k| -Tab.for_keg(k).time.to_i },
+      *versioned.sort_by(&:version),
+    ]
     if kegs.empty?
       puts "Not installed"
     else