Convert pool arguments to int

Failing to do so may cause dangerous misbehaviours such as an unbounded
pool (because of lame comparison operators in Python 2).

Fix ticket #220.

NEWS

@@ -16,6 +16,8 @@ What's new in psycopg 2.5.4
 - Added :sql:`jsonb` support for PostgreSQL 9.4.
 - Fixed segfault if COPY statements are executed instead of using the
   proper methods (:ticket:`#219`).
+- Force conversion of pool arguments to integer to avoid potentially unbounded
+  pools (:ticket:`#220`).
 - Don't ignore silently the `cursor.callproc` argument without a length.
 - Added a few errors missing from `~psycopg2.errorcodes`, defined by
   PostgreSQL but not documented.

lib/pool.py

@@ -42,8 +42,8 @@ class AbstractConnectionPool(object):
         with given parameters. The connection pool will support a maximum of
         about 'maxconn' connections.        
         """
-        self.minconn = minconn
-        self.maxconn = maxconn
+        self.minconn = int(minconn)
+        self.maxconn = int(maxconn)
         self.closed = False
         
         self._args = args