Use Hex.State agent for identifier config

Switch from a raw `System.get_env` to using the normalized state
agent. Also prevent STDERR from leaking when called outside of a git
repository.

Author: sorentwo

lib/hex/state.ex

@@ -112,6 +112,11 @@ defmodule Hex.State do
       default: nil,
       config: [:cacerts_path]
     },
+    no_repo_identifier: %{
+      env: ["HEX_NO_REPO_IDENTIFIER"],
+      default: false,
+      config: [:no_repo_identifier]
+    },
     no_short_urls: %{
       env: ["HEX_NO_SHORT_URLS"],
       config: [:no_short_urls],

lib/hex/utils.ex

@@ -338,14 +338,16 @@ defmodule Hex.Utils do
   - The current directory isn't within a git repository
   """
   def repo_identifier do
-    case Process.get(:hex_repo_identifier, :unset) do
+    case Process.get(:hex_repo_identifier) do
       cached when is_binary(cached) ->
         cached
 
-      _ ->
-        with flag when flag in ["1", "true"] <- System.get_env("HEX_REPO_IDENTIFIER", "1"),
+      nil ->
+        cmd_opts = ~w(rev-list --max-parents=0 HEAD)
+
+        with false <- Hex.State.get(:no_repo_identifier),
              path when is_binary(path) <- System.find_executable("git"),
-             {output, 0} <- System.cmd("git", ["rev-list", "--max-parents=0", "HEAD"]) do
+             {output, 0} <- System.cmd("git", cmd_opts, stderr_to_stdout: true) do
           identifier =
             output
             |> String.trim()

test/hex/utils_test.exs

@@ -1,10 +1,6 @@
 defmodule Hex.UtilsTest do
   use ExUnit.Case
 
-  setup do
-    on_exit(fn -> Process.delete(:hex_repo_identifier) end)
-  end
-
   describe "repo_identifier/0" do
     test "an identifier is included within a repository" do
       assert Hex.Utils.repo_identifier() =~ ~r/^[a-f0-9]{64}$/
@@ -29,13 +25,13 @@ defmodule Hex.UtilsTest do
     end
 
     test "identifier is nil when disabled by an environment variable" do
-      System.put_env("HEX_REPO_IDENTIFIER", "0")
-      refute Hex.Utils.repo_identifier()
+      System.put_env("HEX_NO_REPO_IDENTIFIER", "1")
+      Hex.State.refresh()
 
-      System.put_env("HEX_REPO_IDENTIFIER", "false")
       refute Hex.Utils.repo_identifier()
     after
-      System.delete_env("HEX_REPO_IDENTIFIER")
+      System.delete_env("HEX_NO_REPO_IDENTIFIER")
+      Hex.State.refresh()
     end
 
     test "the identifier is cached within the current process" do