It works because . does not match newlines by default.
i think betterworld knows this =)
the point is, should .* match the empty string between foo\n and the end?

update: 

"\n" =~ /\n.*\z/; # matches
"\n" =~ /.*\z/;   # doesn't match. huh?
"\n" =~ /[^\n]*\z/; # matches. ??

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In reply to Re^2: Strange regex to test for newlines: /.*\z/ by tinita
in thread Strange regex to test for newlines: /.*\z/ by betterworld

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