The checked-in `.gitattributes` file allows to control some aspects of the repository. In particular, it is [interpreted by github-linguist](https://github.com/github/linguist/blob/master/docs/overrides.md), the engine taking care of programming language analysis, to provide exclusion for vendored libraries and direct detection rules. As a practical example, `.t` files used for cram and Mercurial tests are detected as Perl by github-linguist. There is even a [dedicated github-linguist issue](https://github.com/github/linguist/issues/1569) on the subject. Projects like [Octobus' mercurial-devel](https://foss.heptapod.net/Octobus/mercurial-devel) and [evolve](https://foss.heptapod.net/mercurial/evolve) could force them to something more appropriate right now. The price to pay would be that it's called `.gitattributes` and that it probably wouldn't be forward compatible with how native Mercurial repositories will work in the not-so-far future. There are potentially other use cases for a shared, checked-in configuration file, but we obviously should not call it`.gitattributes`. Does something similar already exist in Mercurial land that we could piggy-back on ? Should we introduce a `.heptapod-attributes`?