Comment 6 for bug 632605

The fix is to handle the error (gio.Error) on closing the stream.
An exception on closing a stream for reading should not lead to a failing application. Even more if the error say that the connection is closed. So my suggestion is to catch the error and log but do not fail.
Here is some code that works for me:

import sys

...

try:
    fd.close()
except:
    LogFactory.getLogger().warn("error on closing the snarfile header after reading: " + sys.exc_info()[1])

With this fix I can now create incremental backups.