(maint) Fix last server environment test

In bb1017f we changed the agent's behavior to fall back to making a
node request if the lastrunfile does not contain a usable environment.

Update the `use_last_server_specified_environment` test to reflect this
change in behavior. Based on test ordering, this test could have passed
if the `lastrunfile` was present when the first agent run started. To
ensure the new behavior is triggered, always clean up the `lastrunfile`
at the beginning of the test.

Author: GabrielNagy

acceptance/tests/environment/use_last_server_specified_environment.rb

@@ -63,15 +63,25 @@
 
   with_puppet_running_on(master, master_opts, testdir) do
     agents.each do |agent|
-      run_agent_on(agent, '--no-daemonize --onetime --verbose') do |result|
-        assert_match(/Info: Using environment 'production'/, result.stdout)
-        assert_match(/Local environment: 'production' doesn't match server specified environment 'special', restarting agent run with environment 'special'/, result.stdout)
-        assert_match(/Notice: special environment/, result.stdout)
+      step 'ensure the lastrunfile is absent for the first run' do
+        on(agent, puppet('config print lastrunfile')) do |command_result|
+          agent.rm_rf(command_result.stdout)
+        end
       end
 
-      run_agent_on(agent, '--no-daemonize --onetime --verbose') do |result|
-        assert_match(/Info: Using environment 'special'/, result.stdout)
-        assert_match(/Notice: special environment/, result.stdout)
+      step 'first run: agent makes a node request to get the environment' do
+        run_agent_on(agent, '--no-daemonize --onetime --debug') do |result|
+          assert_match(/Local environment: 'production' doesn't match server specified node environment 'special', switching agent to 'special'/, result.stdout)
+          assert_match(/Debug: HTTP GET .*\/puppet\/v3\/node/, result.stdout)
+          assert_match(/Notice: special environment/, result.stdout)
+        end
+      end
+
+      step 'second run: agent uses the environment from lastrunfile' do
+        run_agent_on(agent, '--no-daemonize --onetime --debug') do |result|
+          assert_match(/Debug: Successfully loaded last environment from the lastrunfile/, result.stdout)
+          assert_match(/Notice: special environment/, result.stdout)
+        end
       end
     end
   end