Try to reproduce an old issue dealing with stale matcher data

spec/wait_for_spec.rb

@@ -92,6 +92,12 @@
         wait_for { progress }.to raise_error(StandardError)
       }.to raise_error(RSpec::Expectations::ExpectationNotMetError)
     end
+
+    it "uses a new matcher instance for each block call" do
+      expect {
+        wait_for { progress.chars }.to contain_exactly(".", ".")
+      }.not_to raise_error
+    end
   end
 
   describe "not_to" do