Vendor RubyDigest to no longer depends on the digest gem

Ref: https://bugs.ruby-lang.org/issues/17873

Ruby 3.1. is making `digest` a default gem, because of this if bundler
depends on it, it might cause already activated issues.

This currently happens if your Gemfile contains a git gem, because
the GitSource makes an MD5 of the repository URL.

Manifest.txt

@@ -227,6 +227,7 @@ bundler/lib/bundler/vendor/connection_pool/lib/connection_pool.rb
 bundler/lib/bundler/vendor/connection_pool/lib/connection_pool/timed_stack.rb
 bundler/lib/bundler/vendor/connection_pool/lib/connection_pool/version.rb
 bundler/lib/bundler/vendor/connection_pool/lib/connection_pool/wrapper.rb
+bundler/lib/bundler/vendor/digest.rb
 bundler/lib/bundler/vendor/fileutils/lib/fileutils.rb
 bundler/lib/bundler/vendor/molinillo/lib/molinillo.rb
 bundler/lib/bundler/vendor/molinillo/lib/molinillo/delegates/resolution_state.rb

bundler/lib/bundler/cli.rb

@@ -790,8 +790,6 @@ def warn_on_outdated_bundler
       command_name = current_command.name
       return if PARSEABLE_COMMANDS.include?(command_name)
 
-      return unless SharedHelpers.md5_available?
-
       latest = Fetcher::CompactIndex.
                new(nil, Source::Rubygems::Remote.new(Bundler::URI("https://rubygems.org")), nil).
                send(:compact_index_client).

bundler/lib/bundler/fetcher/compact_index.rb

@@ -68,10 +68,6 @@ def fetch_spec(spec)
       compact_index_request :fetch_spec
 
       def available?
-        unless SharedHelpers.md5_available?
-          Bundler.ui.debug("FIPS mode is enabled, bundler can't use the CompactIndex API")
-          return nil
-        end
         if fetch_uri.scheme == "file"
           Bundler.ui.debug("Using a local server, bundler won't use the CompactIndex API")
           return false

bundler/lib/bundler/shared_helpers.rb

@@ -145,6 +145,13 @@ def print_major_deprecations!
       Bundler.ui.warn message
     end
 
+    def trap(signal, override = false, &block)
+      prior = Signal.trap(signal) do
+        block.call
+        prior.call unless override
+      end
+    end
+
     def ensure_same_dependencies(spec, old_deps, new_deps)
       new_deps = new_deps.reject {|d| d.type == :development }
       old_deps = old_deps.reject {|d| d.type == :development }
@@ -176,22 +183,9 @@ def pretty_dependency(dep, print_source = false)
       msg
     end
 
-    def md5_available?
-      return @md5_available if defined?(@md5_available)
-      @md5_available = begin
-        require "openssl"
-        ::OpenSSL::Digest.digest("MD5", "")
-        true
-      rescue LoadError
-        true
-      rescue ::OpenSSL::Digest::DigestError
-        false
-      end
-    end
-
     def digest(name)
-      require "digest"
-      Digest(name)
+      require "bundler/vendor/digest"
+      Digest.const_get(name)
     end
 
     def write_to_gemfile(gemfile_path, contents)

bundler/lib/bundler/source/rubygems/remote.rb

@@ -21,8 +21,6 @@ def initialize(uri)
         #
         def cache_slug
           @cache_slug ||= begin
-            return nil unless SharedHelpers.md5_available?
-
             cache_uri = original_uri || uri
 
             host = cache_uri.to_s.start_with?("file://") ? nil : cache_uri.host