Merge pull request #786 from gruntwork-io/rho/branch-issue

Use git branch --show-current because it works when there are no commits

modules/git/git.go

@@ -20,7 +20,27 @@ func GetCurrentBranchName(t testing.TestingT) string {
 
 // GetCurrentBranchNameE retrieves the current branch name or
 // empty string in case of detached state.
+// Uses branch --show-current, which was introduced in git v2.22.
+// Falls back to rev-parse for users of the older version, like Ubuntu 18.04.
 func GetCurrentBranchNameE(t testing.TestingT) (string, error) {
+	cmd := exec.Command("git", "branch", "--show-current")
+	bytes, err := cmd.Output()
+	if err != nil {
+		return GetCurrentBranchNameOldE(t)
+	}
+
+	name := strings.TrimSpace(string(bytes))
+	if name == "HEAD" {
+		return "", nil
+	}
+
+	return name, nil
+}
+
+// GetCurrentBranchNameOldE retrieves the current branch name or
+// empty string in case of detached state. This uses the older pattern
+// of `git rev-parse` rather than `git branch --show-current`.
+func GetCurrentBranchNameOldE(t testing.TestingT) (string, error) {
 	cmd := exec.Command("git", "rev-parse", "--abbrev-ref", "HEAD")
 	bytes, err := cmd.Output()
 	if err != nil {