Rollup 12 Service Activity bug and Microsoft's Public Apology

Our users found an odd bug on our service activity form (where we have custom javascript to set a lookup field based on some business logic).

The error below started coming up after rollup 12. I explain steps to reproduce in more detail here:
http://stackoverflow.com/questions/14819416/bug-in-crm-service-appointment-forms-javascript-causing-form-save-error/14989557#14989557

We ended up getting an acknowledgement of the bug from Microsoft and they pushed a fix online, but will have to wait for rollup 13 for the fix on-premise. They are damaging their credibility with these bugs and I am not the only one to notice. It even prompted a public apology from Bob Stutz, a Microsoft VP. Apologies can't give me or my customers their time back.

>System.Web.HttpUnhandledException: Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #52178855: System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.FormatException: Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx).
>   at System.Guid.GuidResult.SetFailure(ParseFailureKind failure, String failureMessageID, Object failureMessageFormatArgument, String failureArgumentName, Exception innerException)
>   at System.Guid.TryParseGuidWithNoStyle(String guidString, GuidResult& result)
>   at System.Guid.TryParseGuid(String g, GuidStyles flags, GuidResult& result)
>   at System.Guid..ctor(String g)
>   at Microsoft.Crm.Application.Platform.AttributeCollection.CreateEnityReferenceFromLookupPropertyValue(String name, Object value, IOrganizationContext context)
>   at Microsoft.Crm.Application.Platform.AttributeCollection.SetEntityProperty(Entity entity, String name, String childAttributeName, Object parentProperty, AttributeMetadata attributeMetadata, Object value, IOrganizationContext context)
>   at Microsoft.Crm.Application.Platform.AttributeCollection.Insert(String name, Object value, Boolean throwIfKeyExists)
>   at Microsoft.Crm.Application.Platform.EntityProxy.SetLookupValueData(XmlNode node)
>   at Microsoft.Crm.Application.Platform.EntityProxy.SetData(XmlNode entityElement)
>   at Microsoft.Crm.Application.Platform.ApplicationEntityCollection.Deserialize(String entitiesXml, String entityType, IOrganizationContext context)
>   at Microsoft.Crm.Application.Platform.EntityProxy.SetData(XmlNode entityElement)
>   at Microsoft.Crm.Application.Forms.EndUserForm.RetrieveParametersForEventDefault()
>   at Microsoft.Crm.Application.Forms.EndUserForm.Initialize(Entity entity)
>   at Microsoft.Crm.Application.Forms.CustomizableForm.Execute(Entity entity, FormDescriptor fd)
>   at Microsoft.Crm.Application.Components.PageHandlers.SchedulableActivityBasePageHandler.ConfigureFormHandler()
>   at Microsoft.Crm.Application.Components.PageHandlers.ServiceAppointmentRecordPageHandler.ConfigureFormHandler()
>   at Microsoft.Crm.Application.Components.PageHandlers.RecordPageHandler.ConfigureFormWrapper()
>   at Microsoft.Crm.Application.Components.Utility.GenericEventProcessor.RaiseEvent(String eventName)
>   at Microsoft.Crm.Application.Controls.PageManager.OnPreRender(EventArgs e)
>   at System.Web.UI.Control.PreRenderRecursiveInternal()
>   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
>   at System.Web.UI.Page.HandleError(Exception e)
>   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
>   at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
>   at System.Web.UI.Page.ProcessRequest()
>   at System.Web.UI.Page.ProcessRequest(HttpContext context)
>   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
>   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)