Add missing MUSTTAIL

ConflictSet.cpp

@@ -3424,7 +3424,7 @@ FLATTEN PRESERVE_NONE void begin(CheckJob *job, CheckContext *context) {
                                 job->readVersion, context->tls)
                      ? ConflictSet::Commit
                      : ConflictSet::Conflict;
-  return complete(job, context);
+  MUSTTAIL return complete(job, context);
 }
 
 } // namespace check_range_read_state_machine