dotnet add package fails when using global.json

[kiranpradeep]

We could reproduce the issue in 5 steps below. To verify if this happen across operating systems, I tried below steps also on a macOS 10.13.4, which gave same results.

1. dotnet --info

.NET Core SDK (reflecting any global.json):
Version: 2.2.401
Commit: 729b316

Runtime Environment:
OS Name: ubuntu
OS Version: 18.04
OS Platform: Linux
RID: ubuntu.18.04-x64
Base Path: /usr/share/dotnet/sdk/2.2.401/

Host (useful for support):
Version: 2.2.6
Commit: 7dac9b1b51

.NET Core SDKs installed:
2.1.301 [/usr/share/dotnet/sdk]
2.2.401 [/usr/share/dotnet/sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.1.1 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.6 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.1 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.6 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.1.1 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.6 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
https://aka.ms/dotnet-download

2. mkdir -p /tmp/bug_squasher && cd /tmp/bug_squasher
3. echo '{"sdk":{"version":"2.1.301"}}' >> global.json
4. dotnet new console
5. dotnet add package Newtonsoft.Json

Writing /tmp/tmpzUOVzz.tmp
info : Adding PackageReference for package 'Newtonsoft.Json' into project '/tmp/bug_squasher/bug_squasher.csproj'.
log : Restoring packages for /tmp/bug_squasher/bug_squasher.csproj...
error: Unable to get repository signature information for source https://api.nuget.org/v3-index/repository-signatures/4.7.0/index.json.
error: The SSL connection could not be established, see inner exception.
error: error:2006D080:BIO routines:BIO_new_file:no such file