Hook for psycopg2 (_dbapi2) cursor not called when using `with resources` constructs

[Vaidic]

While using opentracing-python-instrumentation for Postgres connection I noticed that the calls made inside the python with resources block are not being traced.

The DB calls made in the following code block is properly traced:

           conn = get_connection() // <--- this method returns the connection object already created at initialization
           cur = conn.cursor()
           cur.execute("SELECT 1")  
           cur.close()

However, if written with with resources the calls are not being traced:

            with get_connection() as conn:
                with conn.cursor() as cur:
                    cur.execute("SELECT 1")  

or even the following does not work :

            conn = get_connection()
            with conn.cursor() as cur:
                cur.execute("SELECT 1")  

Based on my debugging, I see that the call to ConnectionWrapper.cursor (in file _dbapi2.py) is not made when the cursor is called from within the with resources block, and then the subsequent calls to 'execute' hook (in psycopg2.py) are never made.