You want a feature in a piece of software but you don’t want to implement it yourself. Luckily, you have access to the repository.
Don’t bother actually working on the feature. Don’t bother putting in a feature request. Instead, add a unit test that checks for the feature and check that in. When the software starts failing unit tests the maintainers will have to decide to toss the test or fix the test by implementing the feature. This would be slightly more effective if the checkin included other tests that were actually useful.
I think this may be apex of Test-Driven Development.