Issue with the Windows image in build pipeline

[shuvendu-lahiri]

Windows pipeline fails often with the following non-deterministic messages about some packages not being found such as Newtonsoft.JSON JsonSub.

Need to manually rerun the Windows job in Azure pipeline to get this to pass.

2020-04-10T20:10:09.4448333Z 
2020-04-10T20:10:13.8160536Z ##[error]Sources\SolidityCFG\SolidityCFG.csproj(0,0): Error NU1101: Unable to find package JsonSubTypes. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages
2020-04-10T20:10:13.8180645Z D:\a\1\s\Sources\SolidityCFG\SolidityCFG.csproj : error NU1101: Unable to find package JsonSubTypes. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages [D:\a\1\s\Sources\VeriSol.sln]
2020-04-10T20:10:13.8186593Z ##[error]Sources\SolidityCFG\SolidityCFG.csproj(0,0): Error NU1102: Unable to find package Microsoft.Extensions.Logging with version (>= 3.1.3)
  - Found 5 version(s) in Microsoft Visual Studio Offline Packages [ Nearest version: 1.1.2 ]
2020-04-10T20:10:13.8189261Z D:\a\1\s\Sources\SolidityCFG\SolidityCFG.csproj : error NU1102: Unable to find package Microsoft.Extensions.Logging with version (>= 3.1.3) [D:\a\1\s\Sources\VeriSol.sln]
2020-04-10T20:10:13.8190492Z D:\a\1\s\Sources\SolidityCFG\SolidityCFG.csproj : error NU1102:   - Found 5 version(s) in Microsoft Visual Studio Offline Packages [ Nearest version: 1.1.2 ] [D:\a\1\s\Sources\VeriSol.sln]
2020-04-10T20:10:13.8195739Z ##[error]Sources\SolidityCFG\SolidityCFG.csproj(0,0): Error NU1102: Unable to find package Microsoft.Extensions.Logging.Console with version (>= 3.1.3)
  - Found 5 version(s) in Microsoft Visual Studio Offline Packages [ Nearest version: 1.1.2 ]
2020-04-10T20:10:13.8197670Z D:\a\1\s\Sources\SolidityCFG\SolidityCFG.csproj : error NU1102: Unable to find package Microsoft.Extensions.Logging.Console with version (>= 3.1.3) [D:\a\1\s\Sources\VeriSol.sln]
2020-04-10T20:10:13.8199035Z D:\a\1\s\Sources\SolidityCFG\SolidityCFG.csproj : error NU1102:   - Found 5 version(s) in Microsoft Visual Studio Offline Packages [ Nearest version: 1.1.2 ] [D:\a\1\s\Sources\VeriSol.sln]
2020-04-10T20:10:13.8202532Z ##[error]Sources\SolidityCFG\SolidityCFG.csproj(0,0): Error NU1102: Unable to find package Newtonsoft.Json with version (>= 12.0.3)
  - Found