Manually closed problem gets reopened when it shouldn't.

It appears that if trigger expression has item that is checked in a scheduled manner(Like Zabbix Agent or SMMP) - than it rechecks items in the expression. Like Zabbix sender or snmptrap.

To reproduce:
1. In Default Linux OS Template create item:
with key: test
Type: Zabbix Trapper, Unsigned Decimal.

2. Create a trigger:
with the following expression:

{Template:test.last()}=1 or {Template:agent.ping.last()}=9999

and 'manual close' ticked.

3. Now go to console and run zabbix_sender:

zabbix_sender -k test -z 127.0.0.1 -o 0 -s "Zabbix server"
zabbix_sender -k test -z 127.0.0.1 -o 1 -s "Zabbix server"

4. You will see new Problem in Problem view or Dashboard. Close it by hand now.

5. You will notice that it gets reopened at the very exact moment when item with key 'agent.ping' is collected.