Keypair create with invalid Json Is not throwing a proper exception

Key pair create with invalid Json request is expected to throw a BadRequest but throwing Http 500 error.

root@ubuntu1204:~/launchpad_nova/nova# curl -i http://127.0.0.1:8774/v2/4c9c3d480e124b34bc5fdc701a038a8c/os-keypairs -X POST -H "X-Auth-Project-Id: demo" -H "User-Agent: python-novaclient" -H "Content-Type: application/json" -H "Accept: application/json" -H "X-Auth-Token: b9e401f79ff44432870d824ee8c1564c" -d'{"alpha": {"name": "test3"}}'
HTTP/1.1 500 Internal Server Error
Via: 1.1 HYSPROXY2, 1.1 HYSPROXY1
Connection: Keep-Alive
Proxy-Connection: Keep-Alive
Content-Length: 128
Date: Wed, 12 Sep 2012 16:05:19 GMT
Content-Type: application/json; charset=UTF-8
X-Compute-Request-Id: req-9fcfd552-8793-4191-83b4-32227e95ae95

{"computeFault": {"message": "The server has either erred or is incapable of performing the requested operation.", "code": 500}}root@ubuntu1204:~/launchpad_nova/nova#
root@ubuntu1204:~/launchpad_nova/nova# vi /var/log/syslog
root@ubuntu1204:~/launchpad_nova/nova# vi /var/log/nova/
root@ubuntu1204:~/launchpad_nova/nova# curl -i http://10.233.52.28:8774/v2/4c9c3d480e124b34bc5fdc701a038a8c/os-keypairs -X POST -H "X-Auth-Project-Id: demo" -H "User-Agent: python-novaclient" -H "Content-Type: application/json" -H "Accept: application/json" -H "X-Auth-Token: b9e401f79ff44432870d824ee8c1564c" -d'{"keypair": {"name2": "test3"}}'
HTTP/1.1 500 Internal Server Error
Via: 1.1 HYSPROXY2, 1.1 HYSPROXY1
Connection: Keep-Alive
Proxy-Connection: Keep-Alive
Content-Length: 128
Date: Wed, 12 Sep 2012 16:09:02 GMT
Content-Type: application/json; charset=UTF-8
X-Compute-Request-Id: req-72f8cb3b-f19f-4b8c-8028-fb8638f66da6

{"computeFault": {"message": "The server has either erred or is incapable of performing the requested operation.", "code": 500}}

Here keypair and name are the mandatory keys that should present in the request body. If user skips those keys in req body and tries to create a keypair, expecting an user readable error message.