Make BenchmarkBashCompletion more honest
Make BenchmarkBashCompletion more honest

name              old time/op    new time/op    delta
BashCompletion-4    67.4µs ± 1%    50.8µs ± 3%  -24.63%  (p=0.000 n=17+19)

name              old alloc/op   new alloc/op   delta
BashCompletion-4    29.5kB ± 0%    29.5kB ± 0%   +0.00%  (p=0.020 n=20+20)

name              old allocs/op  new allocs/op  delta
BashCompletion-4       253 ± 0%       253 ± 0%     ~     (all equal)

anthonyfok/cobra,spf13/cobra,liggitt/cobra