Since IPC::Lite is just pushing the variable into your namespace as a global variable, I'd think a fully-scoped name would eliminate the error:

use IPC::Lite (); # always load it, why not?

if ($saving) {
  IPC::Lite->import( Key => $0, qw(@urls) );
}

push @::urls, '...';
[download]

Of course, if your namespace isn't main, then substitute appropriately, e.g., @LearnedByError::urls. Or just turn off the warning for undeclared variables around the code that uses @urls - to some people this is the "right" solution, though I'd prefer avoiding it where possible.

Though, to be honest, I'm surprised our @urls before the IPC::Lite->import... doesn't work.