TaskVine Executor: make sure factory scratch dir exists (#3786)

# Fixes
#3089 

## Type of change
- Bug fix

Author: colinthomas-z80

parsl/executors/taskvine/factory.py

@@ -1,4 +1,5 @@
 import logging
+import os
 
 from parsl.executors.taskvine.errors import TaskVineFactoryFailure
 from parsl.process_loggers import wrap_with_logs
@@ -43,6 +44,9 @@ def _taskvine_factory(should_stop, factory_config):
     factory.max_workers = factory_config.max_workers
     factory.workers_per_cycle = factory_config.workers_per_cycle
 
+    # create scratch dir if factory process gets ahead of the manager.
+    os.makedirs(factory.scratch_dir, exist_ok=True)
+
     if factory_config.worker_options:
         factory.extra_options = factory_config.worker_options
     factory.timeout = factory_config.worker_timeout