Ensure that "PRAGMA wal_checkpoint = TRUNCATE|FULL|RESTART" block on other connections and truncate the database file as required even if the entire wal file has already been checkpointed.

FossilOrigin-Name: 53429689d4fcf472edbc89cc50b5e69ba3270634

src/main.c

@@ -1966,6 +1966,7 @@ int sqlite3_wal_checkpoint_v2(
     rc = SQLITE_ERROR;
     sqlite3ErrorWithMsg(db, SQLITE_ERROR, "unknown database: %s", zDb);
   }else{
+    db->busyHandler.nBusy = 0;
     rc = sqlite3Checkpoint(db, iDb, eMode, pnLog, pnCkpt);
     sqlite3Error(db, rc);
   }