ExpandFileContent silently no-ops on Substring / Regexp with both FileName and Content set to true

ExpandFileContent silently no-ops on Substring / Regexp with both FileName and Content set to true: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). I'm building search queries against zoekt and ran into a confusing edge case with query.ExpandFileContent .