clean source path as well to allow directory rename cycle

mmv.go

@@ -47,6 +47,11 @@ func buildRenames(files map[string]string) ([]rename, error) {
 		if src == "" || dst == "" {
 			return nil, &emptyPathError{}
 		}
+		if d := filepath.Clean(src); d != src {
+			delete(files, src)
+			src = d
+			files[src] = dst
+		}
 		if d := filepath.Clean(dst); d != dst {
 			dst = d
 			files[src] = dst

mmv_test.go

@@ -170,6 +170,22 @@ func TestRename(t *testing.T) {
 			},
 			err: &sameDestinationError{"baz"},
 		},
+		{
+			name: "clean source path",
+			files: map[string]string{
+				"foo":  "bar",
+				"bar/": "foo/",
+			},
+			cnt: 3,
+			contents: map[string]string{
+				"foo": "0",
+				"bar": "1",
+			},
+			expected: map[string]string{
+				"bar": "0",
+				"foo": "1",
+			},
+		},
 		{
 			name: "cleaned path same destination error",
 			files: map[string]string{