fix(mix/scm): handle GIT_TRACE=1

lib/mix/lib/mix/scm/git.ex

@@ -420,13 +420,21 @@ defmodule Mix.SCM.Git do
         version =
           ["--version"]
           |> git!("")
-          |> parse_version()
+          |> parse_version_output()
 
         Mix.State.put(:git_version, version)
         version
     end
   end
 
+  defp parse_version_output(output) do
+    output
+    |> String.trim()
+    |> String.split("\n")
+    |> List.last()
+    |> parse_version()
+  end
+
   defp parse_version("git version " <> version) do
     version
     |> String.split(".")
@@ -435,6 +443,10 @@ defmodule Mix.SCM.Git do
     |> List.to_tuple()
   end
 
+  defp parse_version(other) do
+    Mix.raise("Unable to parse Git version from: #{inspect(other)}")
+  end
+
   defp format_version(version) do
     version |> Tuple.to_list() |> Enum.join(".")
   end

lib/mix/test/mix/tasks/deps.git_test.exs

@@ -72,6 +72,27 @@ defmodule Mix.Tasks.DepsGitTest do
     end)
   end
 
+  test "gets Git repos with git trace enabled" do
+    on_exit(fn ->
+      System.delete_env("GIT_TRACE")
+      :ets.delete(Mix.State, :git_version)
+    end)
+
+    System.put_env("GIT_TRACE", "1")
+    :ets.delete(Mix.State, :git_version)
+
+    in_fixture("no_mixfile", fn ->
+      Mix.Project.push(GitApp)
+
+      Mix.Tasks.Deps.Get.run([])
+      message = "* Getting git_repo (#{fixture_path("git_repo")})"
+      assert_received {:mix_shell, :info, [^message]}
+
+      assert File.read!("mix.lock") =~
+               ~r/"git_repo": {:git, #{inspect(fixture_path("git_repo"))}, "[a-f0-9]+", \[\]}/
+    end)
+  end
+
   test "gets and updates Git repos with submodules" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(GitSubmodulesApp)