Sorry. I swapped the ends around when posting. That should [901,0], but the point still stands:

$some_pos = 950;

print +( $_->[1] < $_->[0] and $_->[1] >= $some_pos )
    ? 'contained'
    : 'not contained' for [901,0];;
not contained
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A range of 100 starting at 901 will wrap around to end at position 0, thereby covering position 950; but your test fails to detect it.