diff --git b/bundler/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent.rb a/bundler/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent.rb
index b3ebf6ecb..546409d03 100644
--- b/bundler/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent.rb
+++ a/bundler/lib/bundler/vendor/net-http-persistent/lib/net/http/persistent.rb
@@ -1,13 +1,8 @@
-require_relative '../../../../../../../../lib/rubygems/vendor/net-http/lib/net/http'
-require_relative '../../../../../../../../lib/rubygems/vendor/uri/lib/uri'
+require_relative '../../../../../vendored_net_http'
+require_relative '../../../../../vendored_uri'
 require 'cgi' # for escaping
 require_relative '../../../../connection_pool/lib/connection_pool'
 
-begin
-  require_relative '../../../../../../../../lib/rubygems/vendor/net-http/lib/net/http/pipeline'
-rescue LoadError
-end
-
 autoload :OpenSSL, 'openssl'
 
 ##
@@ -712,23 +707,6 @@ def max_retries= retries
     reconnect
   end
 
-  ##
-  # Pipelines +requests+ to the HTTP server at +uri+ yielding responses if a
-  # block is given.  Returns all responses received.
-  #
-  # See
-  # Gem::Net::HTTP::Pipeline[https://rdoc.info/gems/net-http-pipeline/Gem::Net/HTTP/Pipeline]
-  # for further details.
-  #
-  # Only if <tt>net-http-pipeline</tt> was required before
-  # <tt>net-http-persistent</tt> #pipeline will be present.
-
-  def pipeline uri, requests, &block # :yields: responses
-    connection_for uri do |connection|
-      connection.http.pipeline requests, &block
-    end
-  end
-
   ##
   # Sets this client's SSL private key
 
