Error codes in summary are reported as negative numbers

[mira01]

Error codes of executed commands are reported in summary with minus sign as shown bellow:

loop --for=0,1,2,3,4,5 --until-error 5 --summary -- exit '$ITEM'
returns
Total runs: 6 Successes: 1 Failures: 5 (-1, -2, -3, -4, -5)

I would expect to return
Total runs: 6 Successes: 1 Failures: 5 (1, 2, 3, 4, 5)