theme_pager does not always respect parameters option while generating pager links.

I have 2 tables with pagers on one of my pages. I generate the pagers like this:

For the first table:
$rendered_table .= theme('pager', array('tags' => array(), 'element' => 0, 'parameters' => array('tab' => 'one')));

For the second table:
$rendered_table .= theme('pager', array('tags' => array(), 'element' => 1, 'parameters' => array('tab' => 'two')));

This generates correct links for the pagers on the initial load.

For the first table 3rd pager link renders as: http://example.com/contact?tab=one&page=3
For the second table 3rd pager link renders as: http://example.com/contact?tab=two&page=3

When I click any pager link, say the 2nd pager link for the first table, it takes me to the page http://example.com/contact?tab=one&page=2

Now, if you observe the pager links for the first and the second table, both have the 'tab' query set to 'one'.

The issue here is the current url query parameter overrides the parameters option requested via the theme_pager function for the second table.

A simple modification to the theme_pager_link should resolve this issue.
Patch attached.