Hi!

One idea is to replace IContentChangeManager service with your own implementation.

[ServiceConfiguration(typeof(IContentChangeManager))]
public class MyContentChangeManager : ContentChangeManager
{
    public MyContentChangeManager(IContentRepository contentRepository, IContentTypeRepository contentTypeRepository, IValidationService validationService, LanguageSelectorFactory languageSelectorFactory, IEnumerable<ICommitter> committers, PropertyResolver propertyResolver, IObjectSerializerFactory serializerFactory, IMetaDataResolver metaDataResolver, IPropertyDefinitionRepository propertyDefinitionRepository, LocalizationService localizationService, ContentAssetHelper contentAssetHelper, Settings settings, SiteDefinitionRepository siteDefinitionRepository, EPiServer.Security.PermissionService permissionService)
        : base(contentRepository, contentTypeRepository, validationService, languageSelectorFactory, committers, propertyResolver, serializerFactory, metaDataResolver, propertyDefinitionRepository, localizationService, contentAssetHelper, settings, siteDefinitionRepository, permissionService)
    {
    }

    public override PropertiesUpdateResult UpdateContentProperties(ContentReference contentReference, IDictionary<string, string> properties, SaveAction saveAction)
    {
        if (IsContentExpirationChanged(properties) && !HttpContext.Current.Items.Contains("ContentExpirationChanged"))
        {
            HttpContext.Current.Items.Add("ContentExpirationChanged", "true");
        }

        return base.UpdateContentProperties(contentReference, properties, saveAction);
    }

    private bool IsContentExpirationChanged(IDictionary<string, string> properties)
    {
        return properties != null && properties.Count == 1 && properties.ContainsKey("iversionable_expire");
    }
}

If you're using StructureMap you can just replace it with the following code:

For<IContentChangeManager>().Use<MyContentChangeManager>();

Then in your PageEventHandler you can check if HttpContext.Current.Items contains the item that gets added in MyContentChangeManager:

var isContentExpirationChanged = HttpContext.Current.Items.Contains("ContentExpirationChanged");

if (isContentExpirationChanged)
{
    bool dontTouchStopPublish = true;
}

Fantastic set of dependencies ;)

Thanks for the suggestions, but I opted for the scheduled jobs path instead. Here is my solution:

	[ScheduledPlugIn(DisplayName = "Sätt avpubliceringsdatum på evenemang", SortIndex = 999)]
	public class SetExpirationOnEventsJob : JobBase
	{
		public override string Execute()
		{
			var contentRepository = ServiceLocator.Current.GetInstance<IContentRepository>();
			var startPage = contentRepository.Get<StartPage>(ContentReference.StartPage);
			var eventPages = contentRepository.GetChildren<EventPage>(startPage.EventsRoot, LanguageSelector.AutoDetect(true));

			var returnString = "";
			var updatedEvents = new Dictionary<string, int>();

			foreach (var eventPage in eventPages)
			{
				var languageVersions = contentRepository.GetLanguageBranches<EventPage>(eventPage.PageLink);
				foreach (var languageVersion in languageVersions)
				{
					var content = languageVersion.CreateWritableClone() as EventPage;
					var updated = EventExpireHelper.SetExpiryDate(content);
					if (updated)
					{
						if (updatedEvents.ContainsKey(languageVersion.Language.EnglishName))
						{
							updatedEvents[languageVersion.Language.EnglishName]++;
						}
						else
						{
							updatedEvents.Add(languageVersion.Language.EnglishName, 1);
						}
						contentRepository.Save(content, SaveAction.ForceCurrentVersion);
						if (content != null) DataFactoryCache.RemovePage(content.ContentLink);
					}
				}
			}

			if (updatedEvents.Any())
			{
				foreach (var keyValuePair in updatedEvents)
				{
					returnString += string.Format("{0} event(s) updated in {1}, ", keyValuePair.Value, keyValuePair.Key);
				}
				returnString = returnString.TrimEnd(new[] { ' ', ',' });
			}
			else
			{
				returnString = "No events updated";
			}

			return returnString;
		}
	}