X-Magento-Tags contains identifiers from removed blocks

[kassner]

Following the investigation and fix of #5897, I noticed that Magento\PageCache\Model\Layout\LayoutPlugin::afterGetOutput sets tags for the related products (i.e.: cat_p_123), even if the related products block is not rendered.

Preconditions

1. Current Magento develop (8e21d5a);

Steps to reproduce

1. Setup as explained in FPC: Upsells & Related product list bug - getIdentities gets called while the block doesn't render and then crashes #5897;
2. Debug headers using varnishlog and navigate to the configurable product ('Product 3' or 'Product 4' as the bug report above);

Expected result

1. X-Magento-Tags will not contain cat_p_123 (given that 123 is the ID of the related product);

Actual result

1. X-Magento-Tags contains cat_p_123 (given that 123 is the ID of the related product);

[magento-engcom-team]

@kassner Thanks for reporting this issue.
Unfortunately, I could not reproduce the issue as you described it. Please add more details to your description of the steps you followed when identifying this issue. Screenshots or logs would be helpful, too.

[magento-engcom-team]

@kassner, we are closing this issue due to inactivity. If you'd like to update it, please reopen the issue.