A triggered timer does not end the task which is left

In my process definition, "task1" has a transition with a due date. When this timer is triggered by the job executor, the transition takes the process to "task2" but "task1" still looks active. For instance, when I run a "task query", instead of only finding "task2", both "task1" and "task2" are found.

Here is my process definition:

<?xml version="1.0" encoding="UTF-8"?>
<process name="test1" xmlns="http://jbpm.org/4.0/jpdl">
<start g="-9,192,48,48" name="start1">
<transition g="-44,-18" name="to task3" to="task3" />
</start>
<end g="490,192,48,48" name="end1" />
<task g="272,189,92,52" name="task1">
<transition g="-42,-18" name="to end1" to="end1" />
<transition g="-45,-18" name="to java1" to="reminder">
<timer duedate="10 seconds" />
</transition>
</task>
<java class="fr.idm.SimpleReminder" g="272,316,92,52" method="remind" name="reminder">
<transition to="task2" />
</java>
<end g="626,319,48,48" name="end2" />
<task g="454,316,92,52" name="task2">
<transition g="-42,-18" name="to end2" to="end2" />
</task>
<task g="113,189,92,52" name="task3">
<transition g="-44,-18" to="task1" name="to end1" />
</task>
</process>

For testing purpose, I introduced "task3" before "task1". It is not listed by the task query, which makes me think that, once "task1" is left, it should no longer be active.

This looks like https://jira.jboss.org/jira/browse/JBPM-967 but the suggested solution does not seem applicable to JBPM 4.x.

I will attached the whole source code.