Clear last_response on errors

When an error occurs, the last_response does not get updated so it's
possible to start inspecting the last last response.

This change makes it so that if an error is raised, clear the
last_response cache to prevent leaky reads

lib/octokit/connection.rb

@@ -155,6 +155,9 @@ def request(method, path, data, options = {})
 
       @last_response = response = agent.call(method, Addressable::URI.parse(path.to_s).normalize.to_s, data, options)
       response.data
+    rescue Octokit::Error => error
+      @last_response = nil
+      raise error
     end
 
     # Executes the request, checking if it was successful
@@ -177,7 +180,7 @@ def sawyer_options
       conn_opts[:proxy] = @proxy if @proxy
       if conn_opts[:ssl].nil?
         conn_opts[:ssl] = { :verify_mode => @ssl_verify_mode } if @ssl_verify_mode
-      else 
+      else
         if @connection_options[:ssl][:verify] == false
           conn_opts[:ssl] = { :verify_mode => 0}
         else

spec/octokit/client_spec.rb

@@ -932,6 +932,22 @@
       expect { Octokit.get('/user') }.to raise_error Octokit::ServerError
     end
 
+    it "resets last_response on errors" do
+      stub_get('/booya').to_return(:status => 200)
+      stub_get('/user').to_return \
+        :status => 509,
+        :headers => {
+          :content_type => "application/json",
+        },
+        :body => {:message => "Bandwidth exceeded"}.to_json
+
+      client = Octokit.client
+      client.get('/booya')
+      expect(client.last_response).to_not be_nil
+      expect { client.get('/user') }.to raise_error Octokit::ServerError
+      expect(client.last_response).to be_nil
+    end
+
     it "handles documentation URLs in error messages" do
       stub_get('/user').to_return \
         :status => 415,