Fixup: setup headers on success.

Called method is setting up response code 503 in case of cache being empty. So
check it out before preparing success response.

master/product/Vifib/Tool/SlapTool.py

@@ -303,8 +303,8 @@ class SlapTool(BaseTool):
     self._logAccess(user, user, '#access %s' % computer_id)
     result = self._getComputerInformation(computer_id, user, True)
 
+    if self.REQUEST.response.getStatus() == 200:
       # Keep in cache server for 7 days
-    self.REQUEST.response.setStatus(200)
       self.REQUEST.response.setHeader('Cache-Control',
                                       'public, max-age=1, stale-if-error=604800')
       self.REQUEST.response.setHeader('Vary',
@@ -312,6 +312,8 @@ class SlapTool(BaseTool):
       self.REQUEST.response.setHeader('Last-Modified', rfc1123_date(DateTime()))
       self.REQUEST.response.setBody(result)
       return self.REQUEST.response
+    else:
+      return result
 
   security.declareProtected(Permissions.AccessContentsInformation,
     'getComputerPartitionCertificate')