Also retry requests where Jira specifies a Retry-after of 0 seconds

When rejecting request with a 429 response, Jira sometimes sends a Retry-after header asking for a backoff of 0 seconds. With the existing retry logic this would mark the request as non-retryable and thus fail the request. With this change, such requests are treated as if Jira had send a retry-after value of 1 second.

This solves one of the issues reported in #1805.

jira/resilientsession.py

@@ -315,7 +315,9 @@ def __recoverable(
             if response.status_code in recoverable_error_codes:
                 retry_after = response.headers.get("Retry-After")
                 if retry_after:
-                    suggested_delay = 2 * int(retry_after)  # Do as told
+                    suggested_delay = 2 * max(
+                        int(retry_after), 1
+                    )  # Do as told but always wait at least a little
                 elif response.status_code == HTTPStatus.TOO_MANY_REQUESTS:
                     suggested_delay = 10 * 2**counter  # Exponential backoff
 

tests/test_resilientsession.py

@@ -65,13 +65,17 @@ def tearDown(self):
 
 
 # Retry test data tuples: (status_code, with_rate_limit_header, with_retry_after_header, retry_expected)
-with_rate_limit = with_retry_after = True
-without_rate_limit = without_retry_after = False
+with_rate_limit = True
+with_retry_after = 1
+without_rate_limit = False
+without_retry_after = None
 status_codes_retries_test_data = [
     # Always retry 429 responses
     (HTTPStatus.TOO_MANY_REQUESTS, with_rate_limit, with_retry_after, True),
+    (HTTPStatus.TOO_MANY_REQUESTS, with_rate_limit, 0, True),
     (HTTPStatus.TOO_MANY_REQUESTS, with_rate_limit, without_retry_after, True),
     (HTTPStatus.TOO_MANY_REQUESTS, without_rate_limit, with_retry_after, True),
+    (HTTPStatus.TOO_MANY_REQUESTS, without_rate_limit, 0, True),
     (HTTPStatus.TOO_MANY_REQUESTS, without_rate_limit, without_retry_after, True),
     # Retry 503 responses only when 'Retry-After' in headers
     (HTTPStatus.SERVICE_UNAVAILABLE, with_rate_limit, with_retry_after, True),
@@ -103,10 +107,10 @@ def test_status_codes_retries(
     mocked_request_method: Mock,
     status_code: int,
     with_rate_limit_header: bool,
-    with_retry_after_header: bool,
+    with_retry_after_header: int | None,
     retry_expected: bool,
 ):
-    RETRY_AFTER_SECONDS = 1 if with_retry_after_header else 0
+    RETRY_AFTER_SECONDS = with_retry_after_header or 0
     RETRY_AFTER_HEADER = {"Retry-After": f"{RETRY_AFTER_SECONDS}"}
     RATE_LIMIT_HEADERS = {
         "X-RateLimit-FillRate": "1",
@@ -125,7 +129,7 @@ def test_status_codes_retries(
 
     mocked_response: Response = Response()
     mocked_response.status_code = status_code
-    if with_retry_after_header:
+    if with_retry_after_header is not None:
         mocked_response.headers.update(RETRY_AFTER_HEADER)
     if with_rate_limit_header:
         mocked_response.headers.update(RATE_LIMIT_HEADERS)