When a conversion extension is used and it returns YAML that begins with “—\n# a comment” the parsing fails.
This does not appear to be an issue when using a .drone.yml file directly.
The parse error returned:
yaml: missing kind attribute.
I have verified that the returned data does have the kind key. Further, removing the starting “—” fixes the issue. Ideally, parsing should be the same and a leading “—” should not cause parse issues.