[ruby/rubygems] Preserve != exclusions in Override :ignore_upper

Switch remove_upper_bounds from a lower-bound allow-list to an
upper-bound reject-list so that operators other than <, <=, and ~>
are kept verbatim. The previous logic, inherited from
Shopify/bundler-ignore-dependency, dropped != exclusions and could
silently re-allow versions the user had explicitly pinned out
(e.g. >= 1.0, != 1.5.0, < 2.0 collapsed to >= 1.0).

https://github.com/ruby/rubygems/commit/7d73d9e035

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2 files changed, 14 insertions, 6 deletions

diff --git a/lib/bundler/override.rb b/lib/bundler/override.rb
index d07dad00ea..1ca6d2fde5 100644
--- a/lib/bundler/override.rb
+++ b/lib/bundler/override.rb
@@ -2,7 +2,7 @@
 
 module Bundler
   class Override
-    LOWER_BOUND_OPERATORS = [">=", ">", "="].freeze
+    UPPER_BOUND_OPERATORS = ["<", "<="].freeze
 
     attr_reader :target, :field, :operation
 
@@ -30,17 +30,19 @@ module Bundler
     def remove_upper_bounds(requirement)
       return Gem::Requirement.default if requirement.nil? || requirement.none?
 
-      lower_bounds = requirement.requirements.filter_map do |op, version|
-        if LOWER_BOUND_OPERATORS.include?(op)
-          [op, version]
+      preserved = requirement.requirements.filter_map do |op, version|
+        if UPPER_BOUND_OPERATORS.include?(op)
+          nil
         elsif op == "~>"
           [">=", version]
+        else
+          [op, version]
         end
       end
 
-      return Gem::Requirement.default if lower_bounds.empty?
+      return Gem::Requirement.default if preserved.empty?
 
-      Gem::Requirement.new(lower_bounds.map {|op, v| "#{op} #{v}" })
+      Gem::Requirement.new(preserved.map {|op, v| "#{op} #{v}" })
     end
   end
 end
diff --git a/spec/bundler/bundler/override_spec.rb b/spec/bundler/bundler/override_spec.rb
index bc813e52fc..da3b5aad87 100644
--- a/spec/bundler/bundler/override_spec.rb
+++ b/spec/bundler/bundler/override_spec.rb
@@ -35,6 +35,12 @@ RSpec.describe Bundler::Override do
         expect(result).to eq(Gem::Requirement.new(">= 1.5"))
       end
 
+      it "preserves != exclusion constraints" do
+        override = described_class.new("rails", :version, :ignore_upper)
+        result = override.apply_to(Gem::Requirement.new(">= 1.0", "!= 1.5.0", "< 2.0"))
+        expect(result).to eq(Gem::Requirement.new(">= 1.0", "!= 1.5.0"))
+      end
+
       it "returns the default requirement when only upper bounds remain" do
         override = described_class.new("rails", :version, :ignore_upper)
         result = override.apply_to(Gem::Requirement.new("< 2.0"))