Pass the previous path when diffing a filtered directory in the files panel

Restricting the diff to the files that a filter leaves visible drops the
delete-side entry of a staged rename, so git shows the file as an
addition instead. Its commit files counterpart already passes both paths;
this brings the files panel in line.

pkg/gui/controllers/files_controller.go

@@ -650,7 +650,9 @@ func (self *FilesController) pathOverridesForDiff(node *filetree.FileNode) []str
 	if !node.IsFile() && self.context().IsFiltering() {
 		var paths []string
 		_ = node.ForEachFile(func(file *models.File) error {
-			paths = append(paths, file.Path)
+			// For a rename we need to pass both paths so that git detects it as
+			// a rename rather than an unrelated delete and add.
+			paths = append(paths, file.Names()...)
 			return nil
 		})
 		return paths

pkg/integration/tests/file/directory_diff_with_renamed_files.go

@@ -98,22 +98,11 @@ var DirectoryDiffWithRenamedFiles = NewIntegrationTest(NewIntegrationTestArgs{
 			)
 
 		t.Views().Main().
-			/* EXPECTED:
 			ContainsLines(
 				Equals("diff --git a/file1 b/dir/file1"),
 				Equals("similarity index 100%"),
 				Equals("rename from file1"),
 				Equals("rename to dir/file1"),
 			)
-			ACTUAL: */
-			ContainsLines(
-				Equals("diff --git a/dir/file1 b/dir/file1"),
-				Equals("new file mode 100644"),
-				Contains("index"),
-				Equals("--- /dev/null"),
-				Equals("+++ b/dir/file1"),
-				Equals("@@ -0,0 +1 @@"),
-				Equals("+file1 content"),
-			)
 	},
 })