Thank you Ken! I thought of this workaround too, and it works marvelously for "[en]" issue, but those were not the only user agent strings that the module was notifying me about.
For example, string
gives me a warning
Version string '20101026Firefox.0' contains invalid data; ignoring: '20101026Firefox.0' at /usr/local/share/perl/5.8.8/Parse/HTTP/UserAgent.pm line 210, <FILES> line 26.
That's why i was asking a more global question how to "shut that module up". :o) I was thinking along the lines how you can say 2>&1 perhaps you could send all output from specified module to /dev/null... I would love to go into the module and tweak it, but i have read-only privileges, and i would try to avoid bothering the person who is responsible for installing these modules for me.
I was researching other user agent modules, but HTML::ParseBrowser thinks that mostly everything is Netscape (when it's clearly Firefox) and HTTP::BrowserDetect thinks that the only IE browser ppl are using is version 4.0 (and as someone said: No offence to that module's writer, but "Is this IE? Yay! Is this 7? Yay" is a bass-ackwards approach to how to detect useragents.)