From 6445e03d1a9e084386eef3ac8ebe16629e5f68cc Mon Sep 17 00:00:00 2001
From: Thomas Dy <thatsmydoing@gmail.com>
Date: Tue, 1 Dec 2020 18:28:20 +0900
Subject: [PATCH] Don't fetch default branch if ref is specified

Currently, we always fetch the default branch with an initial git clone
and then fetch the ref after if it's specified. This changes it to only
make one fetch instead of two if a ref is specified.
---
 api/internal/git/cloner.go | 72 +++++++++++++++++++++++---------------
 1 file changed, 43 insertions(+), 29 deletions(-)

diff --git a/api/internal/git/cloner.go b/api/internal/git/cloner.go
index 6df8dca21..7323f20bc 100644
--- a/api/internal/git/cloner.go
+++ b/api/internal/git/cloner.go
@@ -29,43 +29,57 @@ func ClonerUsingGitExec(repoSpec *RepoSpec) error {
 
 	cmd := exec.Command(
 		gitProgram,
-		"clone",
-		"--depth=1",
-		repoSpec.CloneSpec(),
+		"init",
 		repoSpec.Dir.String())
 	out, err := cmd.CombinedOutput()
 	if err != nil {
-		log.Printf("Error cloning git repo: %s", out)
+		log.Printf("Error initializing git repo: %s", out)
 		return errors.Wrapf(
 			err,
-			"trouble cloning git repo %v in %s",
-			repoSpec.CloneSpec(), repoSpec.Dir.String())
+			"trouble initializing git repo in %s",
+			repoSpec.Dir.String())
 	}
 
-	if repoSpec.Ref != "" {
-		cmd = exec.Command(
-			gitProgram,
-			"fetch",
-			"--depth=1",
-			"origin",
-			repoSpec.Ref)
-		cmd.Dir = repoSpec.Dir.String()
-		out, err = cmd.CombinedOutput()
-		if err != nil {
-			log.Printf("Error fetching ref: %s", out)
-			return errors.Wrapf(err, "trouble fetching %s", repoSpec.Ref)
-		}
+	cmd = exec.Command(
+		gitProgram,
+		"remote",
+		"add",
+		"origin",
+		repoSpec.CloneSpec())
+	cmd.Dir = repoSpec.Dir.String()
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		log.Printf("Error adding remote: %s", out)
+		return errors.Wrapf(err, "trouble adding remote %s", repoSpec.CloneSpec())
+	}
 
-		cmd = exec.Command(
-			gitProgram,
-			"checkout",
-			"FETCH_HEAD")
-		cmd.Dir = repoSpec.Dir.String()
-		out, err = cmd.CombinedOutput()
-		if err != nil {
-			log.Printf("Error checking out ref: %s", out)
-			return errors.Wrapf(err, "trouble checking out %s", repoSpec.Ref)
-		}
+	ref := "HEAD"
+	if repoSpec.Ref != "" {
+		ref = repoSpec.Ref
+	}
+
+	cmd = exec.Command(
+		gitProgram,
+		"fetch",
+		"--depth=1",
+		"origin",
+		ref)
+	cmd.Dir = repoSpec.Dir.String()
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		log.Printf("Error fetching ref: %s", out)
+		return errors.Wrapf(err, "trouble fetching %s", ref)
+	}
+
+	cmd = exec.Command(
+		gitProgram,
+		"checkout",
+		"FETCH_HEAD")
+	cmd.Dir = repoSpec.Dir.String()
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		log.Printf("Error checking out ref: %s", out)
+		return errors.Wrapf(err, "trouble checking out %s", ref)
 	}
 
 	cmd = exec.Command(