Python PYODBC: Previous SQL was not a query

Question

I have gone through:

• Error "Previous SQL was not a query" in Python?
• MSSQL2008 - Pyodbc - Previous SQL was not a query
• How to check if a result set is empty?

However none of them have resolved the issue.

The snippet from my db.py file is as follows:

result = cursor.execute(self.sql,self.params)
if result is None:
    self.data = []
else:
    self.data = [dict(zip([key[0] for key in cursor.description], row)) for row in result.fetchall()]
cnxn.close()
return self.data

This works for every SQL and stored procedure I have thrown at it except for this one

seq = request.form['seq']
s = 'EXEC sp_add ?, ?'
p = (udf.get_username(), int(seq))
l = Conn.testing(db="testingDatabase",sql=s,params=p)

I get the error:

Previous SQL was not a query

The SQL:

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

ALTER PROCEDURE sp_add
    @user nvarchar(50),
    @seq int
AS
BEGIN
    SET NOCOUNT ON;

    insert into tblName (userCol,seqCol) VALUES (@user,@seq)
END
GO

The stored procedure runs and the row gets inserted but the error shows up.

What I did instead was:

result = cursor.execute(self.sql,self.params)
cnxn.close()
return str(result)

This returns:

EXEC sp_add ?, ?

Why does it return that? Why does it return the statement I just passed to it?

In my SP, if I tag on a SELECT statement then the issue goes away.

Any suggestions other than the hack just mentioned?