Auto-restore on broke netstandard projects #2446

Description

I ran autorestore on a sln and after that the netstandard projects did not build.
In the diff I saw - <Import Project="..\.paket\Paket.Restore.targets" /> and nothing added.

Repro steps

1. Mixed sln with net461 & netstandard1.3 projects
2. Run paket.exe auto-restore on

here is the commit where I ran auto-restore.

Expected behavior

The sln to build like before.

Actual behavior

The netstandard projects did not build, rest of projects worked as before.

Known workarounds

Revert.