Revision tree field

[pmelab]

Provide and manage "parent" and "merge parent" fields in revision tables of all revisionable content entities.

• Field item implementation
• Field item test case
• Field constraint and validation
• Pre-install hook to add field to content entities
• Add revision parent base field definitions
• Auto-set revision parent on entity create

Resolution: To be moved into 8.7 core.

[amateescu]

Agreed with the resolution: core patch

The work is done in: https://www.drupal.org/project/drupal/issues/2725523