gh-134262: Fix off by one errors in download retry functions (GH-134867)

Author: emmatyping

PCbuild/get_external.py

@@ -12,7 +12,7 @@
 def retrieve_with_retries(download_location, output_path, reporthook,
                           max_retries=7):
     """Download a file with exponential backoff retry and save to disk."""
-    for attempt in range(max_retries):
+    for attempt in range(max_retries + 1):
         try:
             resp = urlretrieve(
                 download_location,

Tools/build/generate_sbom.py

@@ -169,7 +169,7 @@ def download_with_retries(download_location: str,
                           base_delay: float = 2.25,
                           max_jitter: float = 1.0) -> typing.Any:
     """Download a file with exponential backoff retry."""
-    for attempt in range(max_retries):
+    for attempt in range(max_retries + 1):
         try:
             resp = urllib.request.urlopen(download_location)
         except urllib.error.URLError as ex: