diff --git a/libs/opsqueue_python/src/producer.rs b/libs/opsqueue_python/src/producer.rs
index ca837f4..2f1e8f3 100644
--- a/libs/opsqueue_python/src/producer.rs
+++ b/libs/opsqueue_python/src/producer.rs
@@ -217,17 +217,19 @@ impl ProducerClient {
         py.allow_threads(|| {
             let prefix = uuid::Uuid::now_v7().to_string();
             tracing::debug!("Uploading submission chunks to object store subfolder {prefix}...");
-            let chunk_count = Python::with_gil(|py| {
-                self.block_unless_interrupted(async {
-                    let chunk_contents = chunk_contents.bind(py);
-                    let stream = futures::stream::iter(chunk_contents)
-                        .map(|item| item.and_then(|item| item.extract()).map_err(Into::into));
+            let chunk_count = self.block_unless_interrupted(async {
+                    let chunk_contents = std::iter::from_fn(move || {
+                        Python::with_gil(|py|
+                            chunk_contents.bind(py).clone().next()
+                                .map(|item| item.and_then(
+                                    |item| item.extract()).map_err(Into::into)))
+                    });
+                    let stream = futures::stream::iter(chunk_contents);
                     self.object_store_client
                         .store_chunks(&prefix, ChunkType::Input, stream)
                         .await
                         .map_err(|e| CError(R(L(e))))
-                })
-            })?;
+                })?;
             let chunk_count = chunk::ChunkIndex::from(chunk_count);
             tracing::debug!("Finished uploading to object store. {prefix} contains {chunk_count} chunks");
 
diff --git a/libs/opsqueue_python/tests/conftest.py b/libs/opsqueue_python/tests/conftest.py
index 978fb4e..3c3d6c1 100644
--- a/libs/opsqueue_python/tests/conftest.py
+++ b/libs/opsqueue_python/tests/conftest.py
@@ -19,6 +19,7 @@
 #     print("A")
 #     multiprocessing.set_start_method('forkserver')
 
+PROJECT_ROOT = Path(__file__).parents[3]
 
 @dataclass
 class OpsqueueProcess:
@@ -34,8 +35,8 @@ def opsqueue_bin_location() -> Path:
         )
         return Path(deriv_path) / "bin" / "opsqueue"
     else:
-        subprocess.run(["cargo", "build", "--quiet", "--bin", "opsqueue"])
-        return Path(".", "target", "debug", "opsqueue")
+        subprocess.run(["cargo", "build", "--quiet", "--bin", "opsqueue"], cwd=PROJECT_ROOT, check=True)
+        return PROJECT_ROOT / Path("target", "debug", "opsqueue")
 
 
 @pytest.fixture
@@ -62,12 +63,11 @@ def opsqueue_service(
         "--database-filename",
         temp_dbname,
     ]
-    cwd = "../../"
     env = os.environ.copy()  # We copy the env so e.g. RUST_LOG and other env vars are propagated from outside of the invocation of pytest
     if env.get("RUST_LOG") is None:
         env["RUST_LOG"] = "off"
 
-    with subprocess.Popen(command, cwd=cwd, env=env) as process:
+    with subprocess.Popen(command, cwd=PROJECT_ROOT, env=env) as process:
         try:
             wrapper = OpsqueueProcess(port=port, process=process)
             yield wrapper