Igor Kushnir authored Jan 27, 2022 and Milian Wolff committed May 28, 2022

commentRepository() returned a reference to StringRepository, which
could be accidentally used directly rather than via the helper function
commentRepositoryOp() that locks the mutex. Prevent such usage mistakes
by encapsulating the mutex and the repository in class CommentRepository
similar to class StaticCacheData in modificationrevision.cpp.