(chocolatey#1759) apikey exit 2 if nothing to do

If enhanced exit codes are enabled, this sets the apikey command to
exit with 2 if there is nothing to do (i.e. if NOCHANGEMESSAGE is
output).

src/chocolatey/infrastructure.app/commands/ChocolateyApiKeyCommand.cs

@@ -134,12 +134,17 @@ Exit codes that normally result from running this command.
 Normal:
  - 0: operation was successful, no issues detected
  - -1 or 1: an error has occurred
+ - 2: nothing to do, apikey already set (enhanced)
+
+NOTE: Starting in v0.10.12, if you have the feature '{0}' 
+ turned on, then choco will provide enhanced exit codes that allow 
+ better integration and scripting.
 
 If you find other exit codes that we have not yet documented, please
  file a ticket so we can document it at
  https://github.com/chocolatey/choco/issues/new/choose.
 
-");
+".format_with(ApplicationParameters.Features.UseEnhancedExitCodes));
             "chocolatey".Log().Info(ChocolateyLoggers.Important, "Options and Switches");
         }
 

src/chocolatey/infrastructure.app/services/ChocolateyConfigSettingsService.cs

@@ -340,7 +340,15 @@ public void set_api_key(ChocolateyConfiguration configuration)
                     _xmlService.serialize(configFileSettings, ApplicationParameters.GlobalConfigFileLocation);
                     this.Log().Info(() => "Updated ApiKey for {0}".format_with(configuration.Sources));
                 }
-                else this.Log().Warn(NO_CHANGE_MESSAGE);
+                else
+                {
+                    this.Log().Warn(NO_CHANGE_MESSAGE);
+
+                    if (configuration.Features.UseEnhancedExitCodes && Environment.ExitCode == 0)
+                    {
+                        Environment.ExitCode = 2;
+                    }
+                }
             }
         }