add a reproducer header

Co-Authored-By: Sukera <[email protected]>

test_harness.jl

@@ -7,6 +7,30 @@ kwargs = Kwargs.kwargs(; coverage=ENV["COVERAGE"],
                                      string("--compiled-modules=", ENV["COMPILED_MODULES"])],
                          test_args=ENV["TEST_ARGS"],
                          )
+commit_info = ""
+try
+    global commit_info
+    using LibGit2
+    repo = LibGit2.GitRepo(pwd())
+    commit = LibGit2.head(repo)
+    commit_sha = LibGit2.GitHash(commit)
+    commit_info = "commit $commit_sha of "
+catch e
+    @info "Could not determine commit of repo in current directory" exception=(e, catch_backtrace())
+end
+
+kwargs_reprs = map(kv -> string(kv[1], "=", repr(kv[2])), collect(kwargs))
+kwargs_repr = join(kwargs_reprs, ", ")
+
+print("""
+│
+│ To reproduce this CI run locally, check out $(commit_info)this repo and
+│ run the following in the environment on julia version $VERSION:
+│
+│ import Pkg
+│ Pkg.test(;$kwargs_repr)
+│
+""")
 
 if parse(Bool, ENV["ANNOTATE"]) && v"1.8pre" < VERSION < v"1.9.0-beta3"
     push!(LOAD_PATH, "@tests-logger-env") # access dependencies