Remove unused broken code in the ctypes-python bindings.
Remove unused broken code in the ctypes-python bindings.

* subversion/bindings/ctypes-python/csvn/repos.py
  (_fs): Remove the txn() method, which was unused and referred to
    '_fs_txn' which doesn't exist. Thus avoid storing a reference to the
    'repos' object during __init__(), which was a circular reference because
    this '_fs' object is itself stored within the 'repos' object.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion