Unable to install Search Engines in Firefox 25.0

[el_gallo_azul]

Steps to reproduce:

I tried to add a couple of Search Engines to Firefox 25.0.

Actual results:

The plugin was not installed. I received the error message "Sorry, you need a Mozilla-based browser (such as Firefox) to install a search plugin.".

Expected results:

A new Search Engine should have been installed.
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1) The release of Ubuntu you are using, via 'lsb_release -rd'
Description: Ubuntu 13.04
Release: 13.04

2) The version of the package you are using
User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:25.0) Gecko/20100101 Firefox/25.0 (Beta/Release)
Build ID: 20131028112627

3) What you expected to happen
See "Expected results" above.

4) What happened instead
See "Actual results" above.

[Chris Coulson (chrisccoulson)]

The Unity addon breaks this. There's already another bug for it somewhere

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Coeur Noir (coeur-noir)]

Still the same problem,

here with FireFox 26 and Ubuntu 13.10