[bundler/bundler] Remove unnecessary condition

The builtin thor's color shell already checks this before printing, and
if not a tty, prints just the string without added color codes.

https://github.com/bundler/bundler/commit/4f62611c87

lib/bundler/ui/shell.rb

@@ -10,7 +10,7 @@ module Bundler
       attr_writer :shell
 
       def initialize(options = {})
-        if options["no-color"] || !$stdout.tty?
+        if options["no-color"]
           Thor::Base.shell = Thor::Shell::Basic
         end
         @shell = Thor::Base.shell.new