/usr/share/perl5/WWW/Mechanize/ is in libwww-mechanize-formfiller-perl 0.12-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/perl5/WWW/Mechanize/FormFiller/
/usr/share/perl5/WWW/Mechanize/FormFiller.pm
/usr/share/perl5/WWW/Mechanize/FormFiller/Value/
/usr/share/perl5/WWW/Mechanize/FormFiller/Value.pm
/usr/share/perl5/WWW/Mechanize/FormFiller/Value/Callback.pm
/usr/share/perl5/WWW/Mechanize/FormFiller/Value/Default.pm
/usr/share/perl5/WWW/Mechanize/FormFiller/Value/Fixed.pm
/usr/share/perl5/WWW/Mechanize/FormFiller/Value/Interactive.pm
/usr/share/perl5/WWW/Mechanize/FormFiller/Value/Keep.pm
/usr/share/perl5/WWW/Mechanize/FormFiller/Value/Random/
/usr/share/perl5/WWW/Mechanize/FormFiller/Value/Random.pm
/usr/share/perl5/WWW/Mechanize/FormFiller/Value/Random/Chars.pm
/usr/share/perl5/WWW/Mechanize/FormFiller/Value/Random/Date.pm
/usr/share/perl5/WWW/Mechanize/FormFiller/Value/Random/Word.pm