Wikimedia Bugzilla is closed!

I could reproduce this bug in the following way:
- go to https://fr.wikipedia.org/wiki/Cumul_des_mandats_en_France
- click on "Modifier" (i.e. Visual Editor)
- set the cursor just after the words « exercice simultané de mandats » (3rd paragraph)
- click on "Plus->Référence" to add a reference
- in the field, enter "toto." 
- click on "Valider" 
(here, I can see a Javascript error in the Web-Developer Firefox plugin: TypeError: group.firstNodes[index2] is undefined (load.php:54))
- click just on the left or on the right of the newly-created reference
=> a few snowmen appear. If you click more, they multiply.

Sometimes other text is duplicated as well and it lead once to a browser crash. Or I get other Javascript errors: "Cannot open another window while another one is active. "

My browser is Firefox 21.0.

See for a discussion (in French): https://fr.wikipedia.org/wiki/Wikip%C3%A9dia:%C3%89diteurVisuel/Avis#.E2.98.83.E2.98.83.E2.98.83.E2.98.83.E2.98.83.E2.98.83.E2.98.83.E2.98.83.E2.98.83.E2.98.83.E2.98.83.E2.98.83.E2.98.83.E2.98.83