Description of problem:
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When a user create a new Keypair, Horizon automatically redirects him to 'Download Keypair'
Despite the fact that the download starts automatically - and works, Clicking 'Download keypair "<Keypair name>"' Will fail with an error.

Version-Release number of selected component (if applicable):
=============================================================
Grizzly 2013-10-24.5
python-django-horizon-2013.1.4-1.el6ost.noarch

How reproducible:
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Always

Steps to Reproduce:
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1. Browse to: Project --> Access & Security --> Keypairs
2. Click Create Keypair and enter any name.
3. Keypair download should start automatically - it doesn't matter if you'll download it or not.
4. Click 'Download keypair "<Keypair name>"'.

Actual results:
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1. The ERROR:
Error: Unable to create keypair: Key pair '<Keypair name>' already exists. (HTTP 409) (Request-ID: req-6a82b529-d8c2-4baf-ad94-0fd87ab1c9b6)

Expected results:
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Keypair .pem file should be downloaded to the user's computer.