From 39304496502c762b3264b117e5f6bd1864108ce9 Mon Sep 17 00:00:00 2001
From: Alistair Scott <ali.scott@gmail.com>
Date: Wed, 6 Sep 2023 13:16:17 +0100
Subject: [PATCH] Don't break existing `GIT_SSH_COMMAND` env var

---
 get_git.go      | 11 +++++++----
 get_git_test.go | 23 +++++++++++++++++++++++
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/get_git.go b/get_git.go
index 2313a3fba..12af61fb6 100644
--- a/get_git.go
+++ b/get_git.go
@@ -319,17 +319,20 @@ func setupGitEnv(cmd *exec.Cmd, sshKeyFile string) {
 		}
 	}
 
-	if len(sshCmd) == 0 {
-		sshCmd = []string{gitSSHCommand + "ssh"}
-	}
-
 	if sshKeyFile != "" {
 		// We have an SSH key temp file configured, tell ssh about this.
 		if runtime.GOOS == "windows" {
 			sshKeyFile = strings.Replace(sshKeyFile, `\`, `/`, -1)
 		}
+
+		if len(sshCmd) == 0 {
+			sshCmd = []string{gitSSHCommand + "ssh"}
+		}
+
 		sshCmd = append(sshCmd, "-i", sshKeyFile)
 		env = append(env, strings.Join(sshCmd, " "))
+	} else if len(sshCmd) > 0 {
+		env = append(env, strings.Join(sshCmd, " "))
 	}
 
 	cmd.Env = env
diff --git a/get_git_test.go b/get_git_test.go
index d123bb5c5..6a2790902 100644
--- a/get_git_test.go
+++ b/get_git_test.go
@@ -699,6 +699,29 @@ func TestGitGetter_setupGitEnvWithExisting_sshKey(t *testing.T) {
 	}
 }
 
+func TestGitGetter_setupGitEnvWithExisting_noSSHKey(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skipf("skipping on windows since the test requires sh")
+		return
+	}
+
+	// start with an existing ssh command configuration
+	os.Setenv("GIT_SSH_COMMAND", "ssh -o StrictHostKeyChecking=no -o IdentitiesOnly=yes")
+	defer os.Setenv("GIT_SSH_COMMAND", "")
+
+	cmd := exec.Command("/bin/sh", "-c", "echo $GIT_SSH_COMMAND")
+	setupGitEnv(cmd, "")
+	out, err := cmd.Output()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	actual := strings.TrimSpace(string(out))
+	if actual != "ssh -o StrictHostKeyChecking=no -o IdentitiesOnly=yes" {
+		t.Fatalf("unexpected GIT_SSH_COMMAND: %q", actual)
+	}
+}
+
 func TestGitGetter_subdirectory_symlink(t *testing.T) {
 	if !testHasGit {
 		t.Skip("git not found, skipping")