diff --git a/planemo/shed/__init__.py b/planemo/shed/__init__.py
index b398728b6..03c414c3a 100644
--- a/planemo/shed/__init__.py
+++ b/planemo/shed/__init__.py
@@ -533,11 +533,7 @@ def _find_repository_id(ctx, shed_context, name, repo_config, **kwds):
     owner = _owner(ctx, repo_config, shed_context, **kwds)
     matching_repository = find_repository(shed_context.tsi, owner, name)
     if matching_repository is None:
-        if not kwds.get("allow_none", False):
-            message = "Failed to find repository for owner/name %s/%s"
-            raise Exception(message % (owner, name))
-        else:
-            return None
+        raise Exception(f"Failed to find repository for owner/name {owner}/{name}")
     else:
         repo_id = matching_repository["id"]
         return repo_id
@@ -1237,7 +1233,6 @@ def find_repository_id(self, ctx, shed_context):
                 shed_context,
                 name=self.name,
                 repo_config=self.config,
-                allow_none=True,
             )
             return repo_id
         except Exception as e:
diff --git a/tests/shed_app_test_utils.py b/tests/shed_app_test_utils.py
index 903b90bcc..1990d5edf 100644
--- a/tests/shed_app_test_utils.py
+++ b/tests/shed_app_test_utils.py
@@ -1,6 +1,6 @@
 import contextlib
-import multiprocessing
 import shutil
+import threading
 from tempfile import mkdtemp
 from typing import NamedTuple
 
@@ -39,10 +39,10 @@ def run():
         app.config["model"] = model
         run_simple("localhost", port, app, use_reloader=False, use_debugger=True)
 
-    p = multiprocessing.Process(target=run)
-    p.start()
+    t = threading.Thread(target=run, daemon=True)
+    t.start()
     network_util.wait_net_service("localhost", port, DEFAULT_OP_TIMEOUT)
-    return MockShed(f"http://localhost:{port}", directory, p, model)
+    return MockShed(f"http://localhost:{port}", directory, t, model)
 
 
 @contextlib.contextmanager
@@ -59,11 +59,11 @@ def mock_shed():
 class MockShed(NamedTuple):
     url: str
     directory: str
-    process: multiprocessing.Process
+    thread: threading.Thread
     model: InMemoryShedDataModel
 
     def shutdown(self):
-        self.process.terminate()
+        self.thread.join(timeout=1)
         shutil.rmtree(self.directory)
 
 
diff --git a/tests/test_shed_operations.py b/tests/test_shed_operations.py
index c7c72bad3..51466b31e 100644
--- a/tests/test_shed_operations.py
+++ b/tests/test_shed_operations.py
@@ -21,14 +21,6 @@ def test_find_repository_id():
         assert repo_id == "r1"
 
 
-def test_find_repository_id_missing():
-    with mock_shed_context() as shed_context:
-        repo_id = shed.find_repository_id(
-            ctx=None, shed_context=shed_context, path=".", name="test_repo_absent", owner="iuc", allow_none=True
-        )
-        assert repo_id is None
-
-
 def test_find_repository_id_missing_exception():
     with mock_shed_context() as shed_context:
         exception = None