From 8bf0c1e4f1342703a22960417a9ff31f21271518 Mon Sep 17 00:00:00 2001
From: "John T. Wodder II" <git@varonathe.org>
Date: Thu, 28 Oct 2021 16:31:11 -0400
Subject: [PATCH 1/3] download: Yield error dict instead of raising when
 dandiset.yaml already exists

---
 dandi/download.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/dandi/download.py b/dandi/download.py
index 122b887eb..0a1ced6ad 100644
--- a/dandi/download.py
+++ b/dandi/download.py
@@ -385,7 +385,8 @@ def _populate_dandiset_yaml(dandiset_path, dandiset, existing):
     mtime = dandiset.modified
     if op.lexists(dandiset_yaml):
         if existing == "error":
-            raise FileExistsError(dandiset_yaml)
+            yield {"status": "error", "message": "already exists"}
+            return
         elif existing == "refresh" and op.lexists(
             op.join(dandiset_path, ".git", "annex")
         ):

From 34a3b93d43f0f88e6b81e4ac435130f8877a49b5 Mon Sep 17 00:00:00 2001
From: "John T. Wodder II" <git@varonathe.org>
Date: Thu, 28 Oct 2021 16:31:44 -0400
Subject: [PATCH 2/3] Don't reuse variables like that

---
 dandi/download.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/dandi/download.py b/dandi/download.py
index 0a1ced6ad..4442808d7 100644
--- a/dandi/download.py
+++ b/dandi/download.py
@@ -397,10 +397,10 @@ def _populate_dandiset_yaml(dandiset_path, dandiset, existing):
         ):
             yield _skip_file("already exists")
             return
-    dandiset = Dandiset(dandiset_path, allow_empty=True)
-    dandiset.path_obj.mkdir(exist_ok=True)  # exist_ok in case of parallel race
-    old_metadata = dandiset.metadata
-    dandiset.update_metadata(metadata)
+    ds = Dandiset(dandiset_path, allow_empty=True)
+    ds.path_obj.mkdir(exist_ok=True)  # exist_ok in case of parallel race
+    old_metadata = ds.metadata
+    ds.update_metadata(metadata)
     os.utime(dandiset_yaml, (time.time(), mtime.timestamp()))
     yield {
         "status": "done",

From 50079f7725c1abc14bc8c144262de88af412090d Mon Sep 17 00:00:00 2001
From: "John T. Wodder II" <git@varonathe.org>
Date: Thu, 28 Oct 2021 16:33:06 -0400
Subject: [PATCH 3/3] download: Do nothing if dandiset.yaml already has correct
 contents

---
 dandi/download.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/dandi/download.py b/dandi/download.py
index 4442808d7..6d9dec7ca 100644
--- a/dandi/download.py
+++ b/dandi/download.py
@@ -26,6 +26,7 @@
     on_windows,
     path_is_subpath,
     pluralize,
+    yaml_load,
 )
 
 lgr = get_logger()
@@ -384,6 +385,10 @@ def _populate_dandiset_yaml(dandiset_path, dandiset, existing):
     lgr.debug("Updating %s from obtained dandiset metadata", dandiset_metadata_file)
     mtime = dandiset.modified
     if op.lexists(dandiset_yaml):
+        with open(dandiset_yaml) as fp:
+            if yaml_load(fp, typ="safe") == metadata:
+                yield _skip_file("no change")
+                return
         if existing == "error":
             yield {"status": "error", "message": "already exists"}
             return