In order to respond to both site builder and developer feedback about core experimental modules in Drupal 8, the committer team is proposing the following changes starting with the Drupal 8.5.x branch (which is now open for development):
- Experimental modules that have alpha stability will only be committed to development branches of Drupal 8.
- If an experimental module has not achieved at least beta-level stability by the alpha1 release of the branch itself, its development will move to the next development branch and the module will not be included in the branch's alpha release. (Or, alternately, the module may be removed from core if there's no clear path to stability.)
- Once an experimental module reaches beta stability, we now require (a) upgrade paths, and (b) backwards compatibility (or a deprecated BC layer) for any API improvements.
For example, if an initiative team wanted to add a new experimental module to core for their desired feature, they could introduce a patch that met the requirements for an experimental module and it could be committed to 8.5.x as an alpha-stability experimental module. However, by 8.5.0-alpha1 (the week of January 17, 2018), either the module would need to be in "beta" level stability (which means its API and data model would be considered stable, with upgrade paths and API BC layers provided when needed), or it would be left in the 8.6.x branch, but removed from the 8.5.x branch before tagging the alpha. 8.5.0 would ship without this new functionality, but (if completed in time) it could be available in the 8.6.0 release.
These policy changes are intended to address a number of frustrations with the existing experimental module process and to better meet expectations for non-core site builders and developers.
For background on this decision or to provide your feedback, see the core policy issue that discusses this proposed change. The issue is open for community feedback until September 6, 2017. Thank you in advance!