This is an example where I think a better idiom for telling people to run commands isn't to give them a shell-prompt starting point, but a Perl one, so here:

$ perl -wE 'for my $d (@INC) { -s "$d/DBD/mysql.pm" and say "$d/DBD/my
+sql.pm" }'
[download]

would become:

C:\strawberry>perl -de 0

Loading DB routines from perl5db.pl version 1.57
Editor support available.

Enter h or 'h h' for help, or 'perldoc perldebug' for more help.

main::(-e:1):   0
[errors from Term::ReadKey to be ignored]
  DB<1> for my $d (@INC) { -s "$d/DBD/mysql.pm" and say "$d/DBD/mysql.
+pm" }
C:/strawberry/perl/vendor/lib/DBD/mysql.pm
[download]

That would then be immune to the vagaries of Windows command lines.