As choroba said, return 1&&0 is different from return 1 and 0.

$ perl -MB::Deparse -e'
   sub f{return 1 and 0;}; 
   sub g{return 1 && 0}; 

   $deparse=B::Deparse->new(); 

   print "f(): ",$deparse->coderef2text(\&f),"\n"; 
   print "g(): ",$deparse->coderef2text(\&g),"\n";' 

f(): {
    0 if return 1;
}
g(): {
    return 0;
}
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