Merge branch 'sg/object-as-type-commit-graph-fix'

The commit-graph facility did not work when in-core objects that are promoted from unknown type to commit (e.g. a commit that is accessed via a tag that refers to it) were involved, which has been corrected. * sg/object-as-type-commit-graph-fix: object_as_type: initialize commit-graph-related fields of 'struct commit'