bug in hoisting through try-catch expr

[Markos Zaharioudakis]

Bug shown by this query:

declare variable $x external;

declare variable $sales :=
<sales>
<sale pid="3" locid="5" qty="3" date="2013-01-01"/>
<sale pid="3" locid="5" qty="5" date="2013-01-02"/>
<sale pid="2" locid="4" qty="1" date="2013-01-01"/>
<sale pid="2" locid="4" qty="1" date="2014-01-01"/>
<sale pid="2" locid="7" qty="1" date="2014-01-01"/>
</sales>;

declare variable $locations :=
<locations>
<loc id="5" city="paris"/>
<loc id="4" city="san fransisco"/>
<loc id="7" city="chania"/>
</locations>;

try
{
  $x * $x
}
catch *
{
  for $s in $sales/sale
  for $l in $locations/loc
  where $s/@locid eq $l/@id
  return <sale>{$l/@city}</sale>
}