missing prefix for searching mysql_clear_password.so

hi developers,

I was sent here from https://github.com/PyMySQL/mysqlclient-python/issues/289

When try to connect to a db with shared plugins like mysql_clear_password.so I get
_mysql_exceptions.OperationalError: (2006, 'Plugin mysql_clear_password could not be loaded: Error loading shared library lib/mariadb/plugin/mysql_clear_password.so: No such file or directory')

My believe is that somehow the prefix (/usr/) is missing from the path, thought I don't know how to debug it further.

STEPS TO REPRODUCE:

docker run -it python:alpine3.8 /bin/sh
apk update
apk add alpine-sdk mariadb-connector-c mariadb-connector-c-dev
pip install mysqlclient

vi /x
------ PASTE THE BELOW ----
#!/usr/bin/env python

import _mysql

db=_mysql.connect(db="mydb", host="remote.example.com", user="user", passwd="password")

------END PASTE ----
chmod 755 /x
/x

If all goes well you get empty output. If it fails (like for me) you get:

Traceback (most recent call last):
File "./x", line 5, in <module>
db=_mysql.connect(db="mydb", host="remote.example.com", user="user", passwd="password") _mysql_exceptions.OperationalError: (2059, 'Plugin mysql_clear_password could not be loaded: Error loading shared library lib/mariadb/plugin/mysql_clear_password.so: No such file or directory')

As it seems from the error message it tries to load from lib/mariadb/plugin/mysql_clear_password.so
This looked a relative path for me so the interesting finding is that if you cd to /usr before run the script it works.

cd /usr
@a63e69f065a7:/usr$ /x
@a63e69f065a7:/usr$

(empty output means it's ok)

Do you have any idea what could set the path wrong and how to fix it?

Thanks for the help in advance