stupid simple retry logic for download

bazelisk.py

@@ -67,6 +67,9 @@
 
 BAZEL_UPSTREAM = "bazelbuild"
 
+BAZEL_DOWNLOAD_RETRIES = 5
+BAZEL_DOWNLOAD_RETRY_WAIT_SECS = 5
+
 
 def decide_which_bazel_version_to_use():
     # Check in this order:
@@ -180,8 +183,7 @@ def get_version_history(bazelisk_directory):
         ),
         # This only handles versions with numeric components, but that is fine
         # since prerelease versions have been excluded.
-        key=lambda version: tuple(int(component)
-                                  for component in version.split('.')),
+        key=lambda version: tuple(int(component) for component in version.split(".")),
         reverse=True,
     )
 
@@ -352,8 +354,16 @@ def download(url, destination_path):
         if creds is not None:
             auth = base64.b64encode(("%s:%s" % (creds[0], creds[2])).encode("ascii"))
             request.add_header("Authorization", "Basic %s" % auth.decode("utf-8"))
-    with closing(urlopen(request)) as response, open(destination_path, "wb") as file:
-        shutil.copyfileobj(response, file)
+
+    tries = BAZEL_DOWNLOAD_RETRIES
+    while tries > 0:
+        try:
+            with closing(urlopen(request)) as response, open(destination_path, "wb") as file:
+                shutil.copyfileobj(response, file)
+                break
+        except Exception:
+            tries -= 1
+            time.sleep(BAZEL_DOWNLOAD_RETRY_WAIT_SECS)
 
 
 def get_bazelisk_directory():