Cannot `pkg> dev .` a package with extensions inside a shared environment?

Following a recent discussion on dev environments, I tried this new workflow of using a shared environment.
But when I used pkg> dev . on a locally downloaded package with extensions (aka weakdeps, introduced in Julia 1.9), this failed spectacularly.

See here for a reproducible example with a lightweight package of mine called HiddenMarkovModels.jl:

The error is the following one (HMMBase.jl is a weakdep of HiddenMarkovModels.jl):

ERROR: `HiddenMarkovModels=84ca31d5-effc-45e0-bfda-5a68cd981f47` depends on `HMMBase=b2b3ca75-8444-5ffa-85e6-af70e2b64fe7`, but no such entry exists in the manifest.

Steps to reproduce:

cd /tmp
git clone
cd HiddenMarkovModels.jl
pkg> activate @mytemporarydevenvironment
pkg> dev .