Add reproduction spec for stack overflow in error formatting

as initially reported in rspec/rspec-rails#2049

The issue occurs when a class defines an `inspect` method which depends on
methods that have been stubbed to e.g. `receive(...).at_most(n).times`.
Failures try to call `inspect` which fails which calls `inspect` which ...

spec/rspec/mocks/partial_double_spec.rb

@@ -152,6 +152,34 @@ def self.inspect
         }.to fail_with(/MyClass/)
       end
 
+      it "formats an error message when inspect fails" do
+        klass = Struct.new(:name) do
+          def inspect
+            "<Inspector(#{name})>"
+          end
+        end
+
+        object = klass.new('foo')
+
+        expect(object).to receive(:name).once.and_return('bar')
+
+        object.name
+
+        expect do
+          object.name
+        end.to raise_error(
+          RSpec::Mocks::MockExpectationError,
+          %|(<Inspector(bar)>).name(no args)\n    expected: 1 time with any arguments\n    received: 2 times|
+        )
+
+        expect do
+          verify object
+        end.to raise_error(
+          RSpec::Mocks::MockExpectationError,
+          %|(<Inspector(bar)>).name(*(any args))\n    expected: 1 time with any arguments\n    received: 2 times with any arguments|
+        )
+      end
+
       it "shares message expectations with clone" do
         expect(object).to receive(:foobar)
         twin = object.clone