More robust git version parsing (#15019)

When GIT_TRACE=1 is set in the env, `mix deps.get` fails with an
unexpected `FunctionClauseError` due to `git --version`'s output
including trace output from git itself:

```
λ GIT_TRACE=1 mix deps.get
* Getting ariel (git@github.com:foo/bar.git - main)
22:17:06.786357 git.c:476               trace: built-in: git init --quiet
22:17:06.798692 git.c:476               trace: built-in: git remote add origin git@github.com:foo/bar.git
22:17:06.804333 git.c:476               trace: built-in: git config remote.origin.url git@github.com:foo/bar.git
** (FunctionClauseError) no function clause matching in Mix.SCM.Git.parse_version/1

    The following arguments were given to Mix.SCM.Git.parse_version/1:

        # 1
        "22:17:06.809548 git.c:476               trace: built-in: git version\ngit version 2.50.1\n"

    Attempted function clauses (showing 1 out of 1):

        defp parse_version(<<"git version ", version::binary>>)

    (mix 1.18.4) lib/mix/scm/git.ex:426: Mix.SCM.Git.parse_version/1
    (mix 1.18.4) lib/mix/scm/git.ex:419: Mix.SCM.Git.git_version/0
    (mix 1.18.4) lib/mix/scm/git.ex:132: Mix.SCM.Git.checkout/2
    (elixir 1.18.4) lib/file.ex:1665: File.cd!/2
    (mix 1.18.4) lib/mix/dep/fetcher.ex:68: Mix.Dep.Fetcher.do_fetch/3
    (mix 1.18.4) lib/mix/dep/converger.ex:238: Mix.Dep.Converger.all/9
    (mix 1.18.4) lib/mix/dep/converger.ex:170: Mix.Dep.Converger.init_all/8
    (mix 1.18.4) lib/mix/dep/converger.ex:110: Mix.Dep.Converger.all/4
```

This patch updates `git_version` to handle trace noise by running
parse on the final output line of `git --version`.

New `deps.git_test` added to exercise the `GIT_TRACE` condition.

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

---------

Co-authored-by: José Valim <jose.valim@gmail.com>

Author: jeffreylo

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)