Only show the first 8 characters of the commit hashes.

bin/brew

@@ -154,7 +154,7 @@ begin
       unless updater.update_from_masterbrew!
         puts "Already up-to-date."
       else
-        puts "Updated Homebrew from #{old_revision} to #{updater.current_revision}."
+        puts "Updated Homebrew from #{old_revision[0,8]} to #{updater.current_revision[0,8]}."
         if updater.pending_formulae_changes?
           ohai "The following formulae were updated:"
           puts_columns updater.updated_formulae