[1.10.x] Fixed #27238 -- Disabled check_pattern_startswith_slash if settings.APPEND_SLASH=False.

Thanks strycore for the report and timgraham for suggesting the
solution.

Backport of 911d9f4ed1a39f945769b7198a419850378f9824 from master

1 files changed, 4 insertions, 0 deletions

diff --git a/django/core/checks/urls.py b/django/core/checks/urls.py
index 8356fc2f00..c151c491dc 100644
--- a/django/core/checks/urls.py
+++ b/django/core/checks/urls.py
@@ -95,6 +95,10 @@ def check_pattern_startswith_slash(pattern):
     Check that the pattern does not begin with a forward slash.
     """
     regex_pattern = pattern.regex.pattern
+    if not settings.APPEND_SLASH:
+        # Skip check as it can be useful to start a URL pattern with a slash
+        # when APPEND_SLASH=False.
+        return []
     if regex_pattern.startswith('/') or regex_pattern.startswith('^/'):
         warning = Warning(
             "Your URL pattern {} has a regex beginning with a '/'. Remove this "