Merge pull request #824 from dandi/gh-819

Don't error when redownloading the same dandiset.yaml file

dandi/download.py

@@ -26,6 +26,7 @@
     on_windows,
     path_is_subpath,
     pluralize,
+    yaml_load,
 )
 
 lgr = get_logger()
@@ -384,8 +385,13 @@ 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":
-            raise FileExistsError(dandiset_yaml)
+            yield {"status": "error", "message": "already exists"}
+            return
         elif existing == "refresh" and op.lexists(
             op.join(dandiset_path, ".git", "annex")
         ):
@@ -396,10 +402,10 @@ 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",