Selective update resolves the graph for selected package

[mrinaldi]

This PR fixes the behavior of selective update (update specifying a package).

The current behavior is to pin the version for all packages, except the one specified, and resolve the whole graph.

This would cause the dependencies of the specified package to be pinned and the package would not be updated if it requires that one or more dependencies need to be updated as well.

For example:
Castle.Core-log4net 3.2.0 depends on Castle.Core >= 3.2.0
Castle.Core-log4net 3.3.3 depends on Castle.Core >= 3.3.3

If I try to update Castle.Core-log4net from 3.2.0 to 3.3.3, it would not succeed because Castle.Core is pinned to 3.2.0.

This PR only resolve the specified package graph.

[forki]

selective update should unpin all transitive package dependencies right now. do you have a repro case?

[forki]

OK, seems you are right and we have a regression.

I tested the following deps file:

source https://nuget.org/api/v2

nuget Castle.Core-log4net

with lock file:

NUGET
  remote: https://nuget.org/api/v2
  specs:
    Castle.Core (3.2.0)
    Castle.Core-log4net (3.2.0)
      Castle.Core (>= 3.2.0)
      log4net (1.2.10)
    log4net (1.2.10)

and it didn't update after paket update nuget Castle.Core-log4net. That is weird. I will now look into your PR.

[forki]

why did these tests change?

[forki]

mhm from looking at the existing code I'm not that sure anymore that this worked before. maybe it only worked in my dreams.

so: