cargo dev crater: cleanup, don't re-download and reextract crates on every run
cargo dev crater: cleanup, don't re-download and reextract crates on every run

graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust