refactor: move RateLimitExceeded to roundup.cgi.exceptions

RateLimitExceeded is an HTTP exception that raises code 429. Move it
to roundup.cgi.exceptions where all the other exceptions that result
in http status codes are located. Also make it inherit from
HTTPException since it is one.

Also add docstrings for all HTTP exceptions and order HTTPExceptions
by status code.

BREAKING CHANGE: if somebody is importing RateLimitExceeded they will
need to change their import. I consider it unlikely anybody is using
RateLimitExceeded. Detectors and extensions are unlikely to raise
RateLimitExceeded. So I am leaving it out of the upgrading doc. Just
doc in change log.

Author: rouilj

CHANGES.txt

@@ -13,6 +13,19 @@ Roundup 2.0 supports Python 3.4 and later. Roundup 2.1.0 supports
 python 3.6 or newer (3.4/3.5 might work, but they are not tested).
 Roundup 2.4.0 is the last release to support Python 2.
 
+2026-XX-XX 2.6.0
+
+Fixed:
+
+- performance improvement to session_dbm.py:clean(). Also add warning
+  log message if clean takes longer than 3 seconds. (John Rouillard)
+- move RateLimitExceeded exception from roundup.exceptions to
+  roundup.cgi.exceptions. Also it now inherits from HTTPException
+  rather than Exception since it is an HTTP exception. (John
+  Rouillard)
+
+Features:
+
 2025-07-13 2.5.0
 
 Fixed:

roundup/cgi/actions.py

@@ -11,8 +11,9 @@
 from roundup.anypy.html import html_escape
 from roundup.anypy.strings import StringIO
 from roundup.cgi import exceptions, templating
+from roundup.cgi.exceptions import RateLimitExceeded
 from roundup.cgi.timestamp import Timestamped
-from roundup.exceptions import RateLimitExceeded, Reject, RejectRaw
+from roundup.exceptions import Reject, RejectRaw
 from roundup.i18n import _
 from roundup.mailgw import uidFromAddress
 from roundup.rate_limit import Gcra, RateLimit

roundup/cgi/client.py

@@ -40,6 +40,7 @@ class SysCallError(Exception):
     IndexerQueryError,
     NotFound,
     NotModified,
+    RateLimitExceeded,
     Redirect,
     SendFile,
     SendStaticFile,
@@ -48,7 +49,6 @@ class SysCallError(Exception):
 from roundup.cgi.form_parser import FormParser
 from roundup.exceptions import (
     LoginError,
-    RateLimitExceeded,
     Reject,
     RejectRaw,
     Unauthorised,

roundup/cgi/exceptions.py

@@ -24,20 +24,25 @@ class Redirect(HTTPException):
     pass
 
 
+class NotModified(HTTPException):
+    """HTTP 304 status code"""
+    pass
+
+
 class NotFound(HTTPException):
     """HTTP 404 status code unless self.response_code is set to
        400 prior to raising exception.
     """
     pass
 
 
-class NotModified(HTTPException):
-    """HTTP 304 status code"""
+class PreconditionFailed(HTTPException):
+    """HTTP 412 status code"""
     pass
 
 
-class PreconditionFailed(HTTPException):
-    """HTTP 412 status code"""
+class RateLimitExceeded(HTTPException):
+    """HTTP 429 error code"""
     pass
 
 

roundup/exceptions.py

@@ -12,10 +12,6 @@ class LoginError(RoundupException):
     pass
 
 
-class RateLimitExceeded(Exception):
-    pass
-
-
 class Unauthorised(RoundupException):
     pass