Function shims_incomplete 

pub fn shims_incomplete() -> bool

Whether an unchained install is missing shims it should have.

Every install before 1.4.0 wrote three files and left core.hooksPath shadowing each repository’s own .git/hooks. Upgrading has to repair that, and the upgrade path only reinstalls when something tells it to — state reports such an install as perfectly Active, because as far as registration goes it is.

Only meaningful for an unchained install: a chained one writes exactly the names the other tool has, which is a different and correct set. chain_drift covers that case.