Fixes #20902: Avoid conflict when Git URL contains embedded username

When cloning Git data sources with URLs containing embedded usernames (e.g., https://user@bitbucket.org/...), NetBox was also passing explicit username/password kwargs to dulwich, causing authentication failures.

Now checks for URL-embedded credentials before passing explicit kwargs.

netbox/core/data_backends.py

@@ -102,7 +102,10 @@ class GitBackend(DataBackend):
             clone_args['pool_manager'] = ProxyPoolManager(self.socks_proxy)
 
         if self.url_scheme in ('http', 'https'):
-            if self.params.get('username'):
+            # Only pass explicit credentials if URL doesn't already contain embedded username
+            # to avoid credential conflicts
+            parsed_url = urlparse(self.url)
+            if not parsed_url.username and self.params.get('username'):
                 clone_args.update(
                     {
                         "username": self.params.get('username'),

netbox/core/tests/test_data_backends.py

@@ -0,0 +1,59 @@
+from unittest.mock import patch
+
+from django.test import TestCase
+
+from core.data_backends import GitBackend
+
+
+class GitBackendCredentialTests(TestCase):
+
+    def _get_clone_kwargs(self, url, **params):
+        backend = GitBackend(url=url, **params)
+
+        with patch('dulwich.porcelain.clone') as mock_clone, \
+             patch('dulwich.porcelain.NoneStream'):
+            try:
+                with backend.fetch():
+                    pass
+            except Exception:
+                pass
+
+            if mock_clone.called:
+                return mock_clone.call_args.kwargs
+            return {}
+
+    def test_url_with_embedded_username_skips_explicit_credentials(self):
+        kwargs = self._get_clone_kwargs(
+            url='https://myuser@bitbucket.org/workspace/repo.git',
+            username='myuser',
+            password='my-api-key'
+        )
+
+        self.assertEqual(kwargs.get('username'), None)
+        self.assertEqual(kwargs.get('password'), None)
+
+    def test_url_without_embedded_username_passes_explicit_credentials(self):
+        kwargs = self._get_clone_kwargs(
+            url='https://bitbucket.org/workspace/repo.git',
+            username='myuser',
+            password='my-api-key'
+        )
+
+        self.assertEqual(kwargs.get('username'), 'myuser')
+        self.assertEqual(kwargs.get('password'), 'my-api-key')
+
+    def test_url_with_embedded_username_no_explicit_credentials(self):
+        kwargs = self._get_clone_kwargs(
+            url='https://myuser@bitbucket.org/workspace/repo.git'
+        )
+
+        self.assertEqual(kwargs.get('username'), None)
+        self.assertEqual(kwargs.get('password'), None)
+
+    def test_public_repo_no_credentials(self):
+        kwargs = self._get_clone_kwargs(
+            url='https://github.com/public/repo.git'
+        )
+
+        self.assertEqual(kwargs.get('username'), None)
+        self.assertEqual(kwargs.get('password'), None)