Fix retry logic for HTTP 5xx errors and network failures

Refactors error handling to retry all 5xx errors (not just 502), network errors (URLError, socket.error, IncompleteRead), and JSON parse errors with exponential backoff and jitter. Respects retry-after and rate limit headers per GitHub API requirements. Consolidates retry logic into make_request_with_retry() wrapper and adds clear logging for retry attempts and failures. Removes dead code from 2016 (errors list, _request_http_error, _request_url_error) that was intentionally disabled in commit 1e5a9048 to fix #29.

Fixes #140, #110, #138

tests/test_pagination.py

@@ -40,7 +40,7 @@ class MockHTTPResponse:
 
 @pytest.fixture
 def mock_args():
-    """Mock args for retrieve_data_gen."""
+    """Mock args for retrieve_data."""
     args = Mock()
     args.as_app = False
     args.token_fine = None
@@ -77,10 +77,8 @@ def test_cursor_based_pagination(mock_args):
         return responses[len(requests_made) - 1]
 
     with patch("github_backup.github_backup.urlopen", side_effect=mock_urlopen):
-        results = list(
-            github_backup.retrieve_data_gen(
-                mock_args, "https://api.github.com/repos/owner/repo/issues"
-            )
+        results = github_backup.retrieve_data(
+            mock_args, "https://api.github.com/repos/owner/repo/issues"
         )
 
     # Verify all items retrieved and cursor was used in second request
@@ -112,10 +110,8 @@ def test_page_based_pagination(mock_args):
         return responses[len(requests_made) - 1]
 
     with patch("github_backup.github_backup.urlopen", side_effect=mock_urlopen):
-        results = list(
-            github_backup.retrieve_data_gen(
-                mock_args, "https://api.github.com/repos/owner/repo/pulls"
-            )
+        results = github_backup.retrieve_data(
+            mock_args, "https://api.github.com/repos/owner/repo/pulls"
         )
 
     # Verify all items retrieved and page parameter was used (not cursor)
@@ -142,10 +138,8 @@ def test_no_link_header_stops_pagination(mock_args):
         return responses[len(requests_made) - 1]
 
     with patch("github_backup.github_backup.urlopen", side_effect=mock_urlopen):
-        results = list(
-            github_backup.retrieve_data_gen(
-                mock_args, "https://api.github.com/repos/owner/repo/labels"
-            )
+        results = github_backup.retrieve_data(
+            mock_args, "https://api.github.com/repos/owner/repo/labels"
         )
 
     # Verify pagination stopped after first request