'add plugin' plugin link gets double encoded and is invalid

Not sure how anyone is using the module atm on d6. All the "Add plugin" links are getting double encoded and are invalid.

For exampe, if I have a field to tamper named "Application Name" I get the following url for 'Add plugin':

<a href="/admin/build/feeds/tamper/add/testing_importer/Application%2520Name">Add plugin</a>

if should be:

<a href="/admin/build/feeds/tamper/add/testing_importer/Application%20Name">Add plugin</a>

I see that on line 33 of feeds_tamper.admin.inc it's getting rawurlencode'd before being sent to the l function. So l is getting 'Application%20Name' and returning 'Application%2520Name'.

For now, simply changing line 50 from

$add = FEEDS_TAMPER_UI_BASE . '/add/' . $importer->id . '/' . $i;

to:

$add = FEEDS_TAMPER_UI_BASE . '/add/' . $importer->id . '/' . $source;

Fixes the problem.

I'll post a proper patch when I get a chance.