Needed:
[x] Wikibase
[] WikibaseLexeme[1]
[] WikibaseQuality (is this needed? Did we merge this with WBQC already?)
[x] WikibaseQualityConstraints
[] PropertySuggester
[] WikibaseMediaInfo[1]
[] mediawiki-vendor
**[1]**
These extensions cannot be compatible with DM 7.x and 8.x at the same time
because DataModel's EntityDocument already implements ClearableEntity as of 8.0.
Local classes can not re-impelment ClearableEntity to avoid fatal
errors.
This was highlighted in https://gerrit.wikimedia.org/r/#/c/mediawiki/extensions/WikibaseLexeme/+/464811/
For this reason we will need to do things in the following order:
# Make all extensions that can be compat with both, compat with both versions. & merge
# Make patches switching the other extensions to 8.0 (Lexeme, MediaInfo, Wikibase) and a mediawiki-vendor patch for 8.0 too
# merge app patches made in step 2 at the same time (so they will all be deployed with the same train)