Probably not directly related to your problem... but note that the $content variable at the end of the line

my $content = get $url or die "Couldn't get $url" unless defined $cont
+ent;
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is not the variable you presumably think it is (i.e. the my $content from the beginning of the line). Rather, it's a global variable... (use strict; would have warned you! 'Global symbol "$content" requires explicit package name...').

Thus it'll remain undefined, even on subsequent iterations of the while loop, after my $content has been sucessfully assigned some content.

I'm not really sure what your intention is behind that unless defined $content, but expect it to not be working one way or another... (at best, it's useless :)