Fix FilterOutDirs on broken symlinks

Broken symlinks would previously be treated as directories and filtered
out, due to the use of IsNotDir (which defaults to false on Stat
errors), but it makes more sense to only filter out elements that are
certainly directories, so use IsDir (which also defaults to false on
Stat errors) and negate its result.

Author: matthijskooijman

list.go

@@ -78,7 +78,7 @@ func (p *PathList) FilterDirs() {
 func (p *PathList) FilterOutDirs() {
 	res := (*p)[:0]
 	for _, path := range *p {
-		if path.IsNotDir() {
+		if !path.IsDir() {
 			res = append(res, path)
 		}
 	}

paths_test.go

@@ -348,11 +348,12 @@ func TestFilterOutDirs(t *testing.T) {
 	pathEqualsTo(t, "_testdata/test.txt.gz", list[6])
 
 	list.FilterOutDirs()
-	require.Len(t, list, 4)
+	require.Len(t, list, 5)
 	pathEqualsTo(t, "_testdata/anotherFile", list[0])
-	pathEqualsTo(t, "_testdata/file", list[1])
-	pathEqualsTo(t, "_testdata/test.txt", list[2])
-	pathEqualsTo(t, "_testdata/test.txt.gz", list[3])
+	pathEqualsTo(t, "_testdata/brokensymlink", list[1])
+	pathEqualsTo(t, "_testdata/file", list[2])
+	pathEqualsTo(t, "_testdata/test.txt", list[3])
+	pathEqualsTo(t, "_testdata/test.txt.gz", list[4])
 }
 
 func TestEquivalentPaths(t *testing.T) {