Fix commit b02190d5

h2/src/main/org/h2/table/RegularTable.java

@@ -505,6 +505,7 @@ public class RegularTable extends TableBase {
         } else {
             if (lockExclusiveSession == null) {
                 if (lockMode == Constants.LOCK_MODE_READ_COMMITTED) {
+                    if (!database.isMultiThreaded()) {
                         // READ_COMMITTED: a read lock is acquired,
                         // but released immediately after the operation
                         // is complete.
@@ -513,6 +514,7 @@ public class RegularTable extends TableBase {
                         // Row level locks work like read committed.
                         return true;
                     }
+                }
                 if (!lockSharedSessions.containsKey(session)) {
                     traceLock(session, exclusive, "ok");
                     session.addLock(this);