From 509b2ff0f087b5cc442896c1246b9fc2bebe2c81 Mon Sep 17 00:00:00 2001
From: Andrey Petrov <andrey.petrov@shazow.net>
Date: Tue, 8 Dec 2015 16:27:26 -0500
Subject: [PATCH] Skip file headers if FromFile/ToFile are empty

---
 difflib/difflib.go | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/difflib/difflib.go b/difflib/difflib.go
index e5005da..003e99f 100644
--- a/difflib/difflib.go
+++ b/difflib/difflib.go
@@ -585,13 +585,15 @@ func WriteUnifiedDiff(writer io.Writer, diff UnifiedDiff) error {
 			if len(diff.ToDate) > 0 {
 				toDate = "\t" + diff.ToDate
 			}
-			err := wf("--- %s%s%s", diff.FromFile, fromDate, diff.Eol)
-			if err != nil {
-				return err
-			}
-			err = wf("+++ %s%s%s", diff.ToFile, toDate, diff.Eol)
-			if err != nil {
-				return err
+			if diff.FromFile != "" || diff.ToFile != "" {
+				err := wf("--- %s%s%s", diff.FromFile, fromDate, diff.Eol)
+				if err != nil {
+					return err
+				}
+				err = wf("+++ %s%s%s", diff.ToFile, toDate, diff.Eol)
+				if err != nil {
+					return err
+				}
 			}
 		}
 		first, last := g[0], g[len(g)-1]
@@ -710,8 +712,10 @@ func WriteContextDiff(writer io.Writer, diff ContextDiff) error {
 			if len(diff.ToDate) > 0 {
 				toDate = "\t" + diff.ToDate
 			}
-			wf("*** %s%s%s", diff.FromFile, fromDate, diff.Eol)
-			wf("--- %s%s%s", diff.ToFile, toDate, diff.Eol)
+			if diff.FromFile != "" || diff.ToFile != "" {
+				wf("*** %s%s%s", diff.FromFile, fromDate, diff.Eol)
+				wf("--- %s%s%s", diff.ToFile, toDate, diff.Eol)
+			}
 		}
 
 		first, last := g[0], g[len(g)-1]