Add :ignore_upper integration coverage

Verify end-to-end that override(..., version: :ignore_upper) drops
< / <= bounds and folds ~> into >= so a Gemfile-pinned 0.9.1 ceiling
no longer prevents myrack 1.0.0 from being chosen.

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

Author: hsbt

spec/install/gemfile/override_spec.rb

@@ -66,4 +66,26 @@
       expect(the_bundle).to include_gems "has_prerelease 1.1.pre"
     end
   end
+
+  context "with a version: :ignore_upper operation" do
+    it "strips a < upper bound on a direct dependency" do
+      install_gemfile <<-G
+        source "https://gem.repo1"
+        override "myrack", version: :ignore_upper
+        gem "myrack", "< 1.0"
+      G
+
+      expect(the_bundle).to include_gems "myrack 1.0.0"
+    end
+
+    it "folds ~> into >= so newer versions become reachable" do
+      install_gemfile <<-G
+        source "https://gem.repo1"
+        override "myrack", version: :ignore_upper
+        gem "myrack", "~> 0.9.1"
+      G
+
+      expect(the_bundle).to include_gems "myrack 1.0.0"
+    end
+  end
 end