[rubygems/rubygems] restart with BUNDLE_VERSION if it's specified

https://github.com/rubygems/rubygems/commit/57cfe7cf8d

lib/bundler/self_manager.rb

@@ -9,26 +9,20 @@ module Bundler
     def restart_with_locked_bundler_if_needed
       return unless needs_switching? && installed?
 
-      restart_with(lockfile_version)
+      restart_with(restart_version)
     end
 
     def install_locked_bundler_and_restart_with_it_if_needed
       return unless needs_switching?
 
-      begin
-        # BUNDLE_VERSION=x.y.z
-        restart_version = Gem::Version.new(Bundler.settings[:version])
-
+      if restart_version == lockfile_version
+        Bundler.ui.info \
+          "Bundler #{current_version} is running, but your lockfile was generated with #{lockfile_version}. " \
+          "Installing Bundler #{lockfile_version} and restarting using that version."
+      else
         Bundler.ui.info \
           "Bundler #{current_version} is running, but your configuration was #{restart_version}. " \
           "Installing Bundler #{restart_version} and restarting using that version."
-      rescue ArgumentError
-        # BUNDLE_VERSION=local
-        restart_version = lockfile_version
-
-        Bundler.ui.info \
-          "Bundler #{current_version} is running, but your lockfile was generated with #{restart_version}. " \
-          "Installing Bundler #{restart_version} and restarting using that version."
       end
 
       install_and_restart_with(restart_version)
@@ -164,7 +158,7 @@ module Bundler
     def installed?
       Bundler.configure
 
-      Bundler.rubygems.find_bundler(lockfile_version.to_s)
+      Bundler.rubygems.find_bundler(restart_version.to_s)
     end
 
     def current_version
@@ -177,5 +171,14 @@ module Bundler
       parsed_version = Bundler::LockfileParser.bundled_with
       @lockfile_version = parsed_version ? Gem::Version.new(parsed_version) : nil
     end
+
+    def restart_version
+      return @restart_version if defined?(@restart_version)
+      # BUNDLE_VERSION=x.y.z
+      @restart_version = Gem::Version.new(Bundler.settings[:version])
+    rescue ArgumentError
+      # BUNDLE_VERSION=local
+      @restart_version = lockfile_version
+    end
   end
 end

spec/bundler/runtime/self_management_spec.rb

@@ -109,6 +109,9 @@ RSpec.describe "Self management", :rubygems => ">= 3.3.0.dev", :realworld => tru
       bundle "config set --local version #{previous_minor}"
       bundle "install", :artifice => "vcr"
       expect(out).to include("Bundler #{Bundler::VERSION} is running, but your configuration was #{previous_minor}. Installing Bundler #{previous_minor} and restarting using that version.")
+
+      bundle "-v"
+      expect(out).to eq(Bundler::VERSION[0] == "2" ? "Bundler version #{previous_minor}" : previous_minor)
     end
 
     it "does not try to install when using bundle config version global" do