It turns out the issue described in
OAK-8012 may also happen without a restart. An incorrect read may happen when the orphaned branch clean up kicks in. There is a race condition in the code before OAK-8012 changes. The read may check the state of an orphaned branch and doesn't see it in the UnmergedBranches map while it is still visible in the DocumentStore.
This issue is about an additional test to verify
OAK-8012 also fixes this situation.