Allow :all target for metadata-field overrides

Remove the temporary "not yet supported" guard so a Gemfile may write
`override :all, required_ruby_version: :ignore_upper` and similar
forms. The version: ban for :all stays — version requirements are
inherently per-gem.

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

Author: hsbt

bundler/lib/bundler/dsl.rb

@@ -195,10 +195,6 @@ def override(target, **operations)
         raise ArgumentError, "`override :all, version:` is not allowed; version requirements are per-gem"
       end
 
-      if target == :all && operations.any?
-        raise ArgumentError, "`override :all` is not yet supported"
-      end
-
       operations.each do |field, operation|
         validate_override_field!(field)
         validate_override_operation!(operation)

spec/bundler/dsl_spec.rb

@@ -444,10 +444,19 @@
       expect(override.operation).to be_nil
     end
 
-    it "raises ArgumentError for `override :all, required_ruby_version:` until :all is implemented" do
-      expect do
-        subject.override(:all, required_ruby_version: :ignore_upper)
-      end.to raise_error(ArgumentError, /`override :all` is not yet supported/)
+    it "stores an Override targeting :all with a metadata field" do
+      subject.override(:all, required_ruby_version: :ignore_upper)
+      override = subject.overrides.first
+      expect(override.target).to eq(:all)
+      expect(override.field).to eq(:required_ruby_version)
+      expect(override.operation).to eq(:ignore_upper)
+    end
+
+    it "stores an Override targeting :all with required_rubygems_version" do
+      subject.override(:all, required_rubygems_version: nil)
+      override = subject.overrides.first
+      expect(override.target).to eq(:all)
+      expect(override.field).to eq(:required_rubygems_version)
     end
 
     it "raises ArgumentError for a non-string, non-symbol, non-nil operation" do