Update of copy_local doesn't regenerate lock file

Description

I have a dependency for which I need to set copy_local: false, it works as expected and also marks all the transitive dependencies the same way. But then I need to reference some of the transitive dependencies directly and, as far as it's resolved with copy_local: false already, I add it and explicitly mark with copy_local: true, but this has no result. Package is still marked as copy_local: false in the resulting lock file, unless I delete file completely and regenerate it from scratch.

Repro steps

1. Add dependency with copy_local: false to the paket.dependencies file

source https://api.nuget.org/v3/index.json

storage: none
framework: net472
nuget Microsoft.Build copy_local: false

And call paket install

2. Add some of the initial package transitive dependencies with copy_local: true

source https://api.nuget.org/v3/index.json

storage: none
framework: net472
nuget Microsoft.Build copy_local: false
nuget Microsoft.Bcl.AsyncInterfaces copy_local: true

And call paket install

Expected behavior

Microsoft.Bcl.AsyncInterfaces should be resolved with copy_local: true

Actual behavior

Microsoft.Bcl.AsyncInterfaces is still copy_local: false in the lock file

Known workarounds

Delete lock file, call paket install again.

Reproduce the issue by editing paket.dependencies and running paket install with the two copy_local settings shown, then inspect the generated lock file. Done means changing a transitive dependency to copy_local: true updates its lock-file entry without deleting the lock file first.