$ diff t/lib.pl.cp  t/lib.pl
36,37c36
< $test_dsn      = $ENV{'DBI_DSN'}
<     ||  "DBI:$dbdriver:dbname=$table_dir";
---
> $test_dsn      = "DBI:$dbdriver:dbname=$table_dir";

##</code><code>##

$ diff t/lib.pl.cp  t/lib.pl
36c36
< $test_dsn      = $ENV{'DBI_DSN'}
---
> $test_dsn      = $ENV{'DBI_DSN'} && $ENV{'DBI_DSN'} =~ m/^DBI:$mdriver/