Other observations...

Tip #6 from the Basic debugging checklist: B::Deparse. The line parses as:

say zip 'ABCDEFGHIJ', 'abcde';
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If I remove the space between zip and the paren:

say zip('ABCDEFGHIJ','abcde');
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the warning goes away, I get the expected output, and it parses differently:

say zip('ABCDEFGHIJ', 'abcde');
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