Unique *.cache filenames fix (#2134)

utils/datasets.py

@@ -372,7 +372,7 @@ class LoadImagesAndLabels(Dataset):  # for training/testing
 
         # Check cache
         self.label_files = img2label_paths(self.img_files)  # labels
-        cache_path = Path(self.label_files[0]).parent.with_suffix('.cache')  # cached labels
+        cache_path = (p if p.is_file() else Path(self.label_files[0]).parent).with_suffix('.cache')  # cached labels
         if cache_path.is_file():
             cache = torch.load(cache_path)  # load
             if cache['hash'] != get_hash(self.label_files + self.img_files) or 'results' not in cache:  # changed