I modified the python sharepoint list library (https://pypi.python.org/pypi/sharepoint/0.4.2). With my changes it is possible to delete and add attachments to a list row. my fork can be found here:

>> https://github.com/pierrejochem/python-sharepoint

Installation

$ git clone https://github.com/pierrejochem/python-sharepoint.git
$ cd python-sharepoint
$ sudo python setup.py install