add store_inputs only if needed

Author: gpetretto

src/jobflow/core/job.py

@@ -1359,7 +1359,7 @@ def prepare_replace(
     """
     Prepare a replacement :obj:`Flow` or :obj:`Job`.
 
-    If the replacement is a ``Flow``, then an additional ``Job`` will be inserted
+    If the replacement is a ``Flow``, then an additional ``Job`` may be inserted
     that maps the output id of the original job to outputs of the ``Flow``.
 
     If the replacement is a ``Flow`` or a ``Job``, then this function pass on
@@ -1383,16 +1383,37 @@ def prepare_replace(
         replace = Flow(jobs=replace)
 
     if isinstance(replace, Flow) and replace.output is not None:
-        # add a job with same UUID as the current job to store the outputs of the
-        # flow; this job will inherit the metadata and output schema of the current
-        # job
-        store_output_job = store_inputs(replace.output)
-        store_output_job.set_uuid(current_job.uuid)
-        store_output_job.index = current_job.index + 1
-        store_output_job.metadata = current_job.metadata
-        store_output_job.output_schema = current_job.output_schema
-        store_output_job._kwargs = current_job._kwargs
-        replace.add_jobs(store_output_job)
+        leaf_nodes = [n for n, d in replace.graph.out_degree() if d == 0]
+        is_last_output_leaf = len(
+            leaf_nodes
+        ) == 1 and replace.output == OutputReference(leaf_nodes[0])
+        if is_last_output_leaf:
+            # the last job of the replace inherits UUID and metadata from
+            # the original job
+            for j in replace.jobs:
+                if j.uuid == leaf_nodes[0]:
+                    leaf_job = j
+                    break
+            leaf_job.set_uuid(current_job.uuid)
+            leaf_job.index = current_job.index + 1
+
+            metadata = leaf_job.metadata
+            metadata.update(current_job.metadata)
+            leaf_job.metadata = metadata
+
+            if not leaf_job.output_schema:
+                leaf_job.output_schema = current_job.output_schema
+        else:
+            # add a job with same UUID as the current job to store the outputs of the
+            # flow; this job will inherit the metadata and output schema of the current
+            # job
+            store_output_job = store_inputs(replace.output)
+            store_output_job.set_uuid(current_job.uuid)
+            store_output_job.index = current_job.index + 1
+            store_output_job.metadata = current_job.metadata
+            store_output_job.output_schema = current_job.output_schema
+            store_output_job._kwargs = current_job._kwargs
+            replace.add_jobs(store_output_job)
 
     elif isinstance(replace, Job):
         # replace is a single Job