Closes #1868 A parent can prelock a table, and then the child, or vice versa without crashing.

This does not add any performance optimizations

git-svn-id: file:///svn/toku/tokudb@13337 c7de825b-a66e-492c-adef-691d508d4ae1

newbrt/brt.c

@@ -4881,7 +4881,8 @@ int
 toku_brt_note_table_lock (BRT brt, TOKUTXN txn)
 {
     if (brt->h->txnid_that_created_or_locked_when_empty != toku_txn_get_txnid(txn) &&
-        brt_is_empty(brt, toku_txn_logger(txn))) {
+        brt_is_empty(brt, toku_txn_logger(txn)) &&
+        brt->h->txnid_that_created_or_locked_when_empty == 0) {
         assert(brt->h->txnid_that_created_or_locked_when_empty == 0);
         brt->h->txnid_that_created_or_locked_when_empty = toku_txn_get_txnid(txn);
         int r = toku_txn_note_brt(txn, brt);