Fix segmentation violation on no commit diff pull

pkg/ghost/types/branch.go

@@ -195,7 +195,6 @@ func apply(ghost GhostBranch, we WorkingEnv, expectedSrcHead string) errors.GitG
 		return git.ApplyDiffBundleFile(we.SrcDir, path.Join(we.GhostDir, ghost.FileName()))
 	case DiffBranch:
 		return git.ApplyDiffPatchFile(we.SrcDir, path.Join(we.GhostDir, ghost.FileName()))
-
 	default:
 		return errors.Errorf("not supported on type = %+v", reflect.TypeOf(ghost))
 	}
@@ -208,6 +207,13 @@ func (bs CommitsBranch) Show(we WorkingEnv, writer io.Writer) errors.GitGhostErr
 
 // Apply applies contents(diff or patch) of this ghost branch on passed working env
 func (bs CommitsBranch) Apply(we WorkingEnv) errors.GitGhostError {
+	if bs.CommitHashFrom == bs.CommitHashTo {
+		log.WithFields(log.Fields{
+			"from": bs.CommitHashFrom,
+			"to":   bs.CommitHashTo,
+		}).Warn("skipping apply ghost commits branch because from-hash and to-hash is the same.")
+		return nil
+	}
 	err := apply(bs, we, bs.CommitHashFrom)
 	if err != nil {
 		return err

pkg/ghost/types/branchspec.go

@@ -112,13 +112,12 @@ func (bs CommitsBranchSpec) PullBranch(we WorkingEnv) (GhostBranch, errors.GitGh
 		log.WithFields(log.Fields{
 			"from": branch.CommitHashFrom,
 			"to":   branch.CommitHashTo,
-		}).Warn("skipping pull and apply ghost commits branch because from-hash and to-hash is the same.")
-		return nil, nil
-	}
-
-	err = pull(branch, we)
-	if err != nil {
-		return nil, err
+		}).Warn("skipping pull ghost commits branch because from-hash and to-hash is the same.")
+	} else {
+		err = pull(branch, we)
+		if err != nil {
+			return nil, err
+		}
 	}
 	return branch, nil
 }