add dest_dir into pythonpath before loading modules (#2692)

Signed-off-by: Nelson Chen <asd3431090@gmail.com>

flytekit/bin/entrypoint.py

@@ -562,7 +562,14 @@ def fast_execute_task_cmd(additional_distribution: str, dest_dir: str, task_exec
 
     # Use the commandline to run the task execute command rather than calling it directly in python code
     # since the current runtime bytecode references the older user code, rather than the downloaded distribution.
-    p = subprocess.Popen(cmd)
+    env = os.environ.copy()
+    if dest_dir is not None:
+        dest_dir_resolved = os.path.realpath(os.path.expanduser(dest_dir))
+        if "PYTHONPATH" in env:
+            env["PYTHONPATH"] += os.pathsep + dest_dir_resolved
+        else:
+            env["PYTHONPATH"] = dest_dir_resolved
+    p = subprocess.Popen(cmd, env=env)
 
     def handle_sigterm(signum, frame):
         logger.info(f"passing signum {signum} [frame={frame}] to subprocess")

tests/flytekit/integration/remote/test_remote.py

@@ -32,6 +32,7 @@
 PROJECT = "flytesnacks"
 DOMAIN = "development"
 VERSION = f"v{os.getpid()}"
+DEST_DIR = "/tmp"
 
 
 @pytest.fixture(scope="session")
@@ -66,6 +67,8 @@ def run(file_name, wf_name, *args):
             CONFIG,
             "run",
             "--remote",
+            "--destination-dir",
+            DEST_DIR,
             "--image",
             IMAGE,
             "--project",