DBD::mysql not reading host from config file

[Danny Rice]

With a dsn like

$dsn =
"dbi:mysql:mysql_ssl=1;mysql_read_default_file=test.cnf;mysql_read_default_group=test_group";
$dbh = DBI->connect($dsn);

seemingly fails to read the host from [test_group] in test.cnf. Adding a
valid host=host_name to the $dsn succeeds in reading the user, password etc
from test.cnf and the connection succeeds

This has been an issue since at least 2020 and I've had to just specify the
host in the $dsn on cygwin.

On linux it does read the host from the config file.