BUG/MINOR: allow commit check to run with one commit only

when starting repository, only one author will be present (only one commit), account for that and for similar situation where only one author exist

Author: oktalz

check.go

@@ -361,9 +361,13 @@ func getLocalCommitData() ([]string, []string, []map[string]string, error) {
 	diffs := []map[string]string{}
 	committer := ""
 	var commit1 *object.Commit
+	var oldestCommit *object.Commit
 	var commit2 *object.Commit
 	for {
 		commit, err := iter.Next()
+		if commit != nil {
+			oldestCommit = commit
+		}
 		if err == io.EOF {
 			break
 		}
@@ -399,6 +403,9 @@ func getLocalCommitData() ([]string, []string, []map[string]string, error) {
 
 	// Get the changes (diff) between the two commits
 	tree1, _ := commit1.Tree()
+	if commit2 == nil {
+		commit2 = oldestCommit
+	}
 	tree2, _ := commit2.Tree()
 	changes, err := object.DiffTree(tree2, tree1)
 	if err != nil {