git-validation: do not fail on an empty commit range

The error could be reproduced with "git-validation -range HEAD..HEAD"

Closes: #36

Signed-off-by: Giuseppe Scrivano <[email protected]>

Author: giuseppe

git/commits.go

@@ -11,6 +11,7 @@ import (
 // Commits returns a set of commits.
 // If commitrange is a git still range 12345...54321, then it will be isolated set of commits.
 // If commitrange is a single commit, all ancestor commits up through the hash provided.
+// If commitrange is an empty commit range, then nil is returned.
 func Commits(commitrange string) ([]CommitEntry, error) {
 	cmdArgs := []string{"git", "log", `--pretty=format:%H`, commitrange}
 	if debug() {
@@ -20,6 +21,9 @@ func Commits(commitrange string) ([]CommitEntry, error) {
 	if err != nil {
 		return nil, err
 	}
+	if len(output) == 0 {
+		return nil, nil
+	}
 	commitHashes := strings.Split(strings.TrimSpace(string(output)), "\n")
 	commits := make([]CommitEntry, len(commitHashes))
 	for i, commitHash := range commitHashes {