User jobs are run with root group

With incron 0.5.5-2:
When a user starts a program with incron, the groups of the
process is set to "root" instead of the user's normal groups.

To reproduce the problem:
Create /tmp/incron_script:
----------------------------------------
#!/bin/bash
echo "$(date):" "$(id)" "$@" >> /tmp/incron_script.log
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chmod 700 /tmp/incron_script
mkdir /tmp/testdir
sudo aptitude install incron
whoami | sudo tee -a /etc/incron.allow
echo '/tmp/testdir IN_ALL_EVENTS /tmp/incron_script $@/$# $%' | incrontab -
sudo /etc/init.d/incron restart
touch /tmp/testdir/foo
cat /tmp/incron_script.log

Actual result:
Fri Feb 1 18:54:02 CET 2008: uid=1000(myusername) gid=1000(myusername) groups=0(root) /tmp/testdir/foo IN_OPEN
Fri Feb 1 18:54:02 CET 2008: uid=1000(myusername) gid=1000(myusername) groups=0(root) /tmp/testdir/foo IN_ATTRIB
Fri Feb 1 18:54:02 CET 2008: uid=1000(myusername) gid=1000(myusername) groups=0(root) /tmp/testdir/foo IN_CLOSE_WRITE

Expected result:
"groups" should contain the groups which the user is in, and definitely not the "root" group.