Make the nuget cache local to the repo (#3370)

* fixes #3368

* Update build nuget cache to be in the repo

build_projects/dotnet-cli-build/PrepareTargets.cs

@@ -261,21 +261,9 @@ namespace Microsoft.DotNet.Cli.Build
         public static BuildTargetResult CheckPackageCache(BuildTargetContext c)
         {
             var ciBuild = string.Equals(Environment.GetEnvironmentVariable("CI_BUILD"), "1", StringComparison.Ordinal);
-
-            if (ciBuild)
-            {
-                // On CI, HOME is redirected under the repo, which gets deleted after every build.
-                // So make NUGET_PACKAGES outside of the repo.
-                var nugetPackages = Path.GetFullPath(Path.Combine(c.BuildContext.BuildDirectory, "..", ".nuget", "packages"));
-                Environment.SetEnvironmentVariable("NUGET_PACKAGES", nugetPackages);
-                Dirs.NuGetPackages = nugetPackages;
-            }
-
-            // Set the package cache location in NUGET_PACKAGES just to be safe
-            if (string.IsNullOrEmpty(Environment.GetEnvironmentVariable("NUGET_PACKAGES")))
-            {
-                Environment.SetEnvironmentVariable("NUGET_PACKAGES", Dirs.NuGetPackages);
-            }
+            
+            // Always set the package cache location local to the build
+            Environment.SetEnvironmentVariable("NUGET_PACKAGES", Dirs.NuGetPackages);
 
             CleanNuGetTempCache();
 

build_projects/dotnet-cli-build/build.ps1

@@ -25,6 +25,7 @@ if($Help)
 
 $env:CONFIGURATION = $Configuration;
 $RepoRoot = "$PSScriptRoot\..\.."
+$env:NUGET_PACKAGES = "$RepoRoot\.nuget\packages"
 
 if($NoPackage)
 {

build_projects/dotnet-cli-build/build.sh

@@ -57,6 +57,9 @@ while [[ $# > 0 ]]; do
     shift
 done
 
+# Set nuget package cache under the repo
+export NUGET_PACKAGES="$REPOROOT/.nuget/packages"
+
 # Set up the environment to be used for building with clang.
 if which "clang-3.5" > /dev/null 2>&1; then
     export CC="$(which clang-3.5)"