It's sometimes useful to be able to have multiple injections active for a particular kind, for example to have some kind of aspect-oriented checking that guards an already present injection. This change makes it so that new injections unify with existing injections rather than replacing them. Signed-off-by: Roger Peppe <rogpeppe@gmail.com> Change-Id: Ib2135df7d8d725df63425309458b87155e174cc2 Reviewed-on: https://cue.gerrithub.io/c/cue-lang/cue/+/1235993 Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com> TryBot-Result: CUEcueckoo <cueckoo@cuelang.org> Reviewed-by: Daniel Martí <mvdan@mvdan.cc>