HARDCODED_CREDENTIALS warning with OS environment variables file when using Coverity Scan

Question

I used Coverity Scan to scan my Python project and got the

HARDCODED_CREDENTIALS warning

which indicated that it was unsafe for me to read the password from the Linux environment variable file. Specifically, I read the password as follows:

import os
MY_PASSWORD=os.getenv("MYPASSWD","owner")

And I use it to connect to MySQL as follows:

mysql_conn=pymysql.connect(password=MY_PASSWORD,...)

How can I fix this warning?