MERGE INTO fails with an error "Timeout trying to lock table"

[mrigger]

Consider the following statements:

CREATE TABLE T0(c0 BOOL, PRIMARY KEY(c0));
MERGE INTO T0(C0) VALUES (TRUE);
MERGE INTO T0(C0) VALUES (2); -- Timeout trying to lock table {0};

Unexpectedly, the second MERGE INTO results in the following error:

Caused by: org.h2.message.DbException: Concurrent update in table "T0": another transaction has updated or deleted the same row [90131-201]
    at org.h2.message.DbException.get(DbException.java:200)
    at org.h2.message.DbException.get(DbException.java:176)
    at org.h2.command.dml.Merge.merge(Merge.java:224)
    at org.h2.command.dml.Merge.update(Merge.java:110)
    at org.h2.command.dml.DataChangeStatement.update(DataChangeStatement.java:45)
    at org.h2.command.CommandContainer.update(CommandContainer.java:173)
    at org.h2.command.Command.executeUpdate(Command.java:250)

I found this based on commit 073bbb8.