[rubygems/rubygems] Remove unnecessary escape sequences

Bundler formatters already take care of this.

rubygems/rubygems@c24415fdd5

lib/bundler/setup.rb

@@ -9,10 +9,10 @@
     begin
       Bundler.ui.silence { Bundler.setup }
     rescue Bundler::BundlerError => e
-      Bundler.ui.warn "\e[31m#{e.message}\e[0m"
+      Bundler.ui.error e.message
       Bundler.ui.warn e.backtrace.join("\n") if ENV["DEBUG"]
       if e.is_a?(Bundler::GemNotFound)
-        Bundler.ui.warn "\e[33mRun `bundle install` to install missing gems.\e[0m"
+        Bundler.ui.warn "Run `bundle install` to install missing gems."
       end
       exit e.status_code
     end

spec/bundler/commands/exec_spec.rb

@@ -836,9 +836,9 @@ def bin_path(a,b,c)
       let(:exit_code) { Bundler::GemNotFound.new.status_code }
       let(:expected) { "" }
       let(:expected_err) { <<-EOS.strip }
-\e[31mCould not find gem 'rack (= 2)' in rubygems repository #{file_uri_for(gem_repo1)}/ or installed locally.
-The source contains the following versions of 'rack': 0.9.1, 1.0.0\e[0m
-\e[33mRun `bundle install` to install missing gems.\e[0m
+Could not find gem 'rack (= 2)' in rubygems repository #{file_uri_for(gem_repo1)}/ or installed locally.
+The source contains the following versions of 'rack': 0.9.1, 1.0.0
+Run `bundle install` to install missing gems.
       EOS
 
       it "runs" do
@@ -863,9 +863,9 @@ def bin_path(a,b,c)
       let(:exit_code) { Bundler::GemNotFound.new.status_code }
       let(:expected) { "" }
       let(:expected_err) { <<-EOS.strip }
-\e[31mCould not find gem 'rack (= 2)' in rubygems repository #{file_uri_for(gem_repo1)}/ or installed locally.
-The source contains the following versions of 'rack': 1.0.0\e[0m
-\e[33mRun `bundle install` to install missing gems.\e[0m
+Could not find gem 'rack (= 2)' in rubygems repository #{file_uri_for(gem_repo1)}/ or installed locally.
+The source contains the following versions of 'rack': 1.0.0
+Run `bundle install` to install missing gems.
       EOS
 
       it "runs" do