[ruby/rubygems] Rewrite the OVERRIDES section without resolving again

An override change made the lockfile count as needing resolution, so `bundle install` fetched the remote index and failed offline when the compact index cache was absent, and `Bundler.setup` re-resolved on boot. The section only needs to be regenerated, which #write_lock already does when the contents differ, and the frozen check still reports the change.

https://github.com/ruby/rubygems/commit/a616f3d1bb

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lib/bundler/definition.rb

@@ -667,8 +667,7 @@ module Bundler
         @locked_spec_with_missing_checksums ||
         empty_checksums_actionable? ||
         @locked_spec_with_missing_deps ||
-        @locked_spec_with_invalid_deps ||
-        @override_changes
+        @locked_spec_with_invalid_deps
     end
 
     def resolve_needed?
@@ -920,6 +919,8 @@ module Bundler
         else
           lockfile_changed_reason
         end
+      elsif @override_changes
+        "the overrides in your gemfile changed"
       else
         "some dependencies were deleted from your gemfile"
       end
@@ -1160,7 +1161,9 @@ module Bundler
 
     # The lockfile records the Gemfile's overrides, so a change to them is a
     # change to the lockfile even when every locked version still satisfies
-    # them.
+    # them. Rewriting the section needs no resolution, so this stays out of
+    # #something_changed?. #write_lock rewrites it because the generated
+    # contents differ, and the frozen check reports it.
     def converge_overrides
       return false unless @locked_gems
 

spec/bundler/install/gemfile/override_spec.rb

@@ -281,6 +281,23 @@ RSpec.describe "override DSL" do
       expect(lockfile).to include("myrack (1.0.0)")
     end
 
+    it "records an override change without fetching from the source" do
+      install_gemfile <<-G
+        source "https://gem.repo1"
+        gem "myrack"
+      G
+
+      gemfile <<-G
+        source "https://gem.repo1"
+        override :all, required_ruby_version: :ignore_upper
+        gem "myrack"
+      G
+
+      FileUtils.rm_rf(compact_index_cache_path)
+      bundle :install, artifice: "fail"
+      expect(lockfile).to include("OVERRIDES\n  :all, required_ruby_version: :ignore_upper\n")
+    end
+
     it "treats equivalent requirement spellings as the same override" do
       install_gemfile <<-G
         source "https://gem.repo1"