Merge pull request #44332 from corhere/backport-20.10/fix-git-windows…

…-environ

[20.10] builder: fix running git commands on Windows

builder/remotecontext/git/gitutils.go

@@ -21,6 +21,7 @@ type gitRepo struct {
 	isolateConfig bool
 }
 
+// CloneOption changes the behaviour of Clone().
 type CloneOption func(*gitRepo)
 
 // WithIsolatedConfig disables reading the user or system gitconfig files when
@@ -213,7 +214,7 @@ func (repo gitRepo) gitWithinDir(dir string, args ...string) ([]byte, error) {
 	cmd := exec.Command("git", args...)
 	cmd.Dir = dir
 	// Disable unsafe remote protocols.
-	cmd.Env = append(cmd.Env, "GIT_PROTOCOL_FROM_USER=0")
+	cmd.Env = append(os.Environ(), "GIT_PROTOCOL_FROM_USER=0")
 
 	if repo.isolateConfig {
 		cmd.Env = append(cmd.Env,