safe_init_db leaks temporary file descriptor

From loggerhead/changecache.py:

def safe_init_db(filename, init_sql):
    # To avoid races around creating the database, we create the db in
    # a temporary file and rename it into the ultimate location.
    fd, temp_path = tempfile.mkstemp(dir=os.path.dirname(filename))
    con = dbapi2.connect(temp_path)
    ...

The file descriptor returned by mkstemp() is completely ignored, and left open forever.

Steps to reproduce:

>>> from loggerhead.changecache import safe_init_db
>>> for i in xrange(100):
... safe_init_db('/tmp/test.sql', "create table RevisionData (revid "
... "binary primary key, data binary)")
...

Then check something like "lsof -n". Look, 100 open copies of /tmp/test.sql!

I assume the simplest fix would be throwing in an "os.close(fd)". It'd be even better if pysqlite had some "connect_to_fd" function, but I don't know if that's the case.