BF: Some bugs in load_previous_manifest

manifest_rules/generate_manifest_file.py

@@ -68,10 +68,12 @@ def load_previous_manifest(release_info):
     # the environment file is not available
     versions = dict(manifest.get('versions', {}))
     for version, builds in versions.items():
+        if version == 'latest':
+            continue
         for i, build in enumerate(list(builds)):
             try:
                 with tempdir():
-                    download_file(build['url'], 'env.yml')
+                    download_file(build['environment'], 'env.yml')
             except Exception:
                 print(f'WARNING: Build environment file '
                       f'is not available: {build}')