Reproducible testing opam repository

This opam repository contains some simple opam packages which do not require the OCaml compiler, mainly for testing the reproducibility tooling for opam.

• env captures the environment variables in a file which is installed,
• fail-random is a non-reproducible package which captures output from /dev/random into a file,
• fail-timestamp is a non-reproducible package which records the current timestamp,
• nothing installs nothing,
• ocaml is an empty package to avoid bootstrapping an OCaml compiler,
• something installs a single file,
• timestamp respects SOURCE_DATE_EPOCH and records a timestamp.