Provide preparation command to be run between benchmarking different commands

[RalfJung]

I want to benchmark two versions of rustc against each other, measuring the build time of a project that however has some build dependencies, downloading and building which I do not want included in the benchmark. However, after using one version of rustc, I need to rm -rf target to enable the other one to build; these are both self-compiled git versions of Rust and their detection of when to recompile because the compiler changed does not work reliably.

Unfortunately, this is not possible with one hyperfine invocation currently; instead I have to resort to calling hyperfine twice and clean the build dir in between. It would be great if hyperfine had a preparation command that was run in-between different commands being benchmarked, but NOT in-between different runs of the same benchmark.

[sharkdp]

Thank you for the feedback!

Sounds like a good idea to me.

[sharkdp]

Fixed via #129 by @colinwahl

[sharkdp]

Released in v1.6.0.