WWW::Mechanize goes through great lengths to behave exactly like the majority of browsers regarding redirects.

As explained in the RFC, it is incorrect for a browser to allow a POST request to be redirected by a 302 server response. Most browsers do it, though, and that's why WWW::Mechanize explicitely allows it via

    push( @{$self->requests_redirectable}, 'POST' );
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although the underlying LWP::UserAgent strictly complies with the standard.