Context

The `to_list` abstraction is meant to return the entire list. Tailable cursors are meant to exist in perpetuity, even after there are no more elements produced in the cursor. As such, this yields unexpected behavior as the cursor could hang indefinitely or raise Exceptions.

Detailed steps to reproduce the problem?

pip install PyMongo

create a capped collection

create a tailable cursor from capped collection

call to_list

```python

import time

import pymongo

client = pymongo.MongoClient()
oplog = client.local.oplog.rs
first = oplog.find().sort('$natural', pymongo.ASCENDING).limit(-1).next()
print(first)
ts = first['ts']

cursor = oplog.find({'ts': {'$gt': ts}},
                        cursor_type=pymongo.CursorType.TAILABLE_AWAIT,
                        oplog_replay=True)
cursor.to_list(length=None)

```

Definition of done: what must be done to consider the task complete?

The exact Python version used, with patch level:

$ python -c "import sys; print(sys.version)"

The exact version of PyMongo used, with patch level:

$ python -c "import pymongo; print(pymongo.version); print(pymongo.has_c())"

Describe how MongoDB is set up. Local vs Hosted, version, topology, load balanced, etc.

The operating system and version (e.g. Windows 7, OSX 10.8, ...)

Web framework or asynchronous network library used, if any, with version (e.g. Django 1.7, mod_wsgi 4.3.0, gevent 1.0.1, Tornado 4.0.2, ...)

Security Vulnerabilities

If you’ve identified a security vulnerability in a driver or any other MongoDB project, please report it according to the instructions here