Windows Python 3.7 .isfile() fix (#9879)

utils/dataloaders.py

@@ -344,7 +344,7 @@ class LoadStreams:
         self.img_size = img_size
         self.stride = stride
         self.vid_stride = vid_stride  # video frame-rate stride
-        sources = Path(sources).read_text().rsplit() if Path(sources).is_file() else [sources]
+        sources = Path(sources).read_text().rsplit() if os.path.isfile(sources) else [sources]
         n = len(sources)
         self.sources = [clean_str(x) for x in sources]  # clean source names for later
         self.imgs, self.fps, self.frames, self.threads = [None] * n, [0] * n, [0] * n, [None] * n

utils/general.py

@@ -426,12 +426,12 @@ def check_file(file, suffix=''):
     # Search/download file (if necessary) and return path
     check_suffix(file, suffix)  # optional
     file = str(file)  # convert to str()
-    if Path(file).is_file() or not file:  # exists
+    if os.path.isfile(file) or not file:  # exists
         return file
     elif file.startswith(('http:/', 'https:/')):  # download
         url = file  # warning: Pathlib turns :// -> :/
         file = Path(urllib.parse.unquote(file).split('?')[0]).name  # '%2F' to '/', split https://url.com/file.txt?auth
-        if Path(file).is_file():
+        if os.path.isfile(file):
             LOGGER.info(f'Found {url} locally at {file}')  # file already exists
         else:
             LOGGER.info(f'Downloading {url} to {file}...')
@@ -586,7 +586,7 @@ def download(url, dir='.', unzip=True, delete=True, curl=False, threads=1, retry
     def download_one(url, dir):
         # Download 1 file
         success = True
-        if Path(url).is_file():
+        if os.path.isfile(url):
             f = Path(url)  # filename
         else:  # does not exist
             f = dir / Path(url).name