Upstream spf13/afero state of the touched files before ac8fa0258e

memmap.go

@@ -263,9 +263,7 @@ func (m *MemMapFs) OpenFile(name string, flag int, perm os.FileMode) (File, erro
 	perm &= chmodBits
 	chmod := false
 	file, err := m.openWrite(name)
-	// O_EXCL is only meaningful together with O_CREATE (POSIX); without
-	// O_CREATE it must not prevent opening an existing file.
-	if err == nil && flag&os.O_EXCL > 0 && flag&os.O_CREATE > 0 {
+	if err == nil && (flag&os.O_EXCL > 0) {
 		return nil, &os.PathError{Op: "open", Path: name, Err: ErrFileExists}
 	}
 	if os.IsNotExist(err) && (flag&os.O_CREATE > 0) {