port upgrade --force shouldn't uninstall if no permission was given to install a missing dependency

[RJVB (René Bertin)]

This is a rare situation, that gave rise to a port being uninstalled in error, I consider:

Given: a port "A" that has a build dependency on port "B1" which itself conflicts with port "B2". Once built, port "A" can co-exist with either "B1" or "B2"; in fact, "A" has a path-style *runtime* dependency on an executable provided by both B1 and B2 (path:bin/bb).

Scenario (leaving out sudo, and ignoring the reasons why I proceeded this way):

`

port deactivate B2 port activate B1 port destroot A port deactivate B1 port activate B2 port -nv upgrade --force A

---> Computing dependencies for A.. The following dependencies will be installed: B1 Continue? [Y/n]: n ---> Deactivating A @version ---> Uninstalling A @version ---> Cleaning A ---> Removing work directory for A ---> Computing dependencies for A.. The following dependencies will be installed: B1 Continue? [Y/n]: n ---> Scanning binaries for linking errors `

I consider that the process should have been aborted when I first refused to install B1. One could also consider that

• the depends_build dependency should be ignored since the build process has been completed
• the depends_run dependency is satisfied by the presence of ${prefix}/bin/bb (provided by B2 at the time).

So in a sense there should be no missing dependency when doing an upgrade .