This test is only activated for >= ruby32 because ruby32 adds support
for assessing coverage within an eval. But the failure isn't anything
to do with eval.

The test tries to call 'ruby' which in Gentoo isn't (yet!) wrapped,
so it ends up calling an older Ruby which then results in 0 coverage
being found. Replace it with a string we can safely sed with the
correct Ruby per-test.
--- a/spec/coverage_for_eval_spec.rb
+++ b/spec/coverage_for_eval_spec.rb
@@ -16,7 +16,7 @@ RSpec.describe "coverage for eval" do
     end
 
     context "foo" do
-      let(:command) { "ruby eval_test.rb" }
+      let(:command) { "@GENTOO_RUBY@ eval_test.rb" }
 
       it "records coverage for erb" do
         expect(@stdout).to include(" 2 / 3 LOC")