Do not set hash to null unnecessarily

This avoids test failures seen in
CommonSwiftClientLiveTest.testObjectOperations.

apis/swift/src/main/java/org/jclouds/openstack/swift/binders/BindSwiftObjectMetadataToRequest.java

@@ -66,7 +66,6 @@ public class BindSwiftObjectMetadataToRequest implements Binder {
       byte[] contentMD5 = object.getInfo().getHash();
       if (contentMD5 != null) {
          // Swizzle hash to ETag
-         object.getInfo().setHash(null);
          request = (R) request.toBuilder()
                .addHeader(HttpHeaders.ETAG,
                      BaseEncoding.base16().lowerCase().encode(contentMD5))