More flexible error message matching

Author: pitr-ch

spec/concurrent/edge/erlang_actor_spec.rb

@@ -546,7 +546,7 @@
               expect(trapped_exit.from).to eq b
               expect(trapped_exit.reason).to eq b.terminated.reason
               expect(trapped_exit.reason).to be_a ArgumentError
-              expect(trapped_exit.reason.message).to eq 'uncaught throw :uncaught'
+              expect(trapped_exit.reason.message).to match /uncaught throw :uncaught/
             end
           end