fix: Fix command building bug

Author: thatguysimon

pact/verify_wrapper.py

@@ -172,7 +172,7 @@ def call_verify(
             command.append('--enable-pending')
 
         if include_wip_pacts_since:
-            command.extend('--include-wip-pacts-since={}'.format(include_wip_pacts_since))
+            command.extend(['--include-wip-pacts-since={}'.format(include_wip_pacts_since)])
 
         headers = kwargs.get('custom_provider_headers', [])
         for header in headers:

tests/cli/test_verify.py

@@ -262,7 +262,8 @@ def test_all_url_options(self, mock_isfile, mock_wrapper):
                                 log_level='INFO',
                                 timeout=60,
                                 verbose=True,
-                                enable_pending=True)
+                                enable_pending=True,
+                                include_wip_pacts_since=None)
 
     @patch("pact.verify_wrapper.VerifyWrapper.call_verify")
     def test_all_broker_options(self, mock_wrapper):