ETAG Header with tempurls in the 'openstack-swift' provider consistently results in a 503 Service unavailable response

I am testing the new openstack-swift provider. For testing purposes, I'm using Rackspace Cloudfiles US as the Swift blobstore. I set the:

provider= 'openstack-swift'
region='IAD'
endpoint='https://identity.api.rackspacecloud.com/v2.0'

While testing PUTs with tempurls, if the ETAG header representing the MD5 checksum is absent, things work just fine.

<pre>
D 09-09 00:34:42.167 main jclouds.headers:56 |::] >> PUT https://storage101.iad3.clouddrive.com/v1/MossoCloudFS_2eb7963d-0f04-4cad-93e0-2227eab8bd7b/my-bucket/my-blob?temp_url_sig=1f66e0b4baa197c416ed81c44927db6c69c3c2f9&temp_url_expires=1410248982 HTTP/1.1
D 09-09 00:34:42.168 main jclouds.headers:56 |::] >> Content-Type: application/octet-stream
D 09-09 00:34:42.168 main jclouds.headers:56 |::] >> Content-Length: 0
D 09-09 00:34:42.619 main o.j.h.i.JavaUrlHttpCommandExecutorService:56 |::] Receiving response -1558734241: HTTP/1.1 201 Created
D 09-09 00:34:42.620 main jclouds.headers:56 |::] << HTTP/1.1 201 Created
</pre>

However, if the ETAG header is present, I always get a 503 Service Unavailable response from Swift.

<pre>
D 09-09 00:46:19.533 main jclouds.headers:56 |::] >> PUT https://storage101.iad3.clouddrive.com/v1/MossoCloudFS_2eb7963d-0f04-4cad-93e0-2227eab8bd7b/my-bucket/my-blob?temp_url_sig=6c03d206cee09054be9189e5b40fb30dc6cb54ae&temp_url_expires=1410249679 HTTP/1.1
D 09-09 00:46:19.534 main jclouds.headers:56 |::] >> ETag: 93b885adfe0da089cdf634904fd59f71
D 09-09 00:46:19.534 main jclouds.headers:56 |::] >> Content-Type: application/octet-stream
D 09-09 00:46:19.534 main jclouds.headers:56 |::] >> Content-Length: 0
D 09-09 00:46:19.713 main o.j.h.i.JavaUrlHttpCommandExecutorService:56 |::] Receiving response -379684309: HTTP/1.1 503 Service Unavailable
D 09-09 00:46:19.714 main jclouds.headers:56 |::] << HTTP/1.1 503 Service Unavailable
D 09-09 00:46:19.714 main jclouds.headers:56 |::] << Date: Tue, 09 Sep 2014 07:46:19 GMT
</pre>

Not sure if this happens only against Rackspace CloudFiles. Haven't tested against other Swift blobstores.