Fix authconfig resolution when credStore is used combined with login()

Signed-off-by: Joffrey F <joffrey@docker.com>

docker/auth.py

@@ -90,9 +90,12 @@ def resolve_authconfig(authconfig, registry=None):
             log.debug(
                 'Using credentials store "{0}"'.format(store_name)
             )
-            return _resolve_authconfig_credstore(
+            cfg = _resolve_authconfig_credstore(
                 authconfig, registry, store_name
             )
+            if cfg is not None:
+                return cfg
+            log.debug('No entry in credstore - fetching from auth dict')
 
     # Default to the public index server
     registry = resolve_index_name(registry) if registry else INDEX_NAME

tests/unit/auth_test.py

@@ -210,6 +210,19 @@ class ResolveAuthTest(unittest.TestCase):
             self.auth_config, auth.resolve_repository_name(image)[0]
         ) is None
 
+    def test_resolve_auth_with_empty_credstore_and_auth_dict(self):
+        auth_config = {
+            'auths': auth.parse_auth({
+                'https://index.docker.io/v1/': self.index_config,
+            }),
+            'credsStore': 'blackbox'
+        }
+        with mock.patch('docker.auth._resolve_authconfig_credstore') as m:
+            m.return_value = None
+            assert 'indexuser' == auth.resolve_authconfig(
+                auth_config, None
+            )['username']
+
 
 class CredStoreTest(unittest.TestCase):
     def test_get_credential_store(self):