I just tried out the new feature Streamline Managed Packages by Deleting Unused Components that came with Spring'15 and deleted a managed VF page called "Advanced Lookup Popup" including its Controller class from my package.
I now push-upgraded an existing customer org and it failed with this error:
This app can't be upgraded. Salesforce has blocked this package upgrade because the new package version removes some Apex code that one or more Visualforce pages or global Visualforce components need in order to function. Please contact your partner with this error information. Provide these component names to your partner. Visualforce Page: Advanced Lookup Popup.
How can I resolve this? Or is this a bug?