DotNetCoreInstaller@1` task failed with non-zero exit code when switch to 1

From @AArnott

Actually, my PR to switch to use UseDotNet@2 can’t complete because 3 PR builds in a row have failed in the dotnet test step. All tests pass, but dotnet.exe returns a nonzero exit code.

Total tests: 246. Passed: 246. Failed: 0. Skipped: 0.
Test Run Successful.
Test execution time: 10.1186 Seconds
     1>Done Building Project "d:\a\1\s\src\StreamJsonRpc.Tests\StreamJsonRpc.Tests.csproj" (VSTest target(s)) -- FAILED.

Build FAILED.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:02:22.63
##[error]Error: The process 'C:\hostedtoolcache\windows\dotnet\dotnet.exe' failed with exit code 1
##[warning]Invalid results file. Make sure the result format of the file 'd:\a\_temp\VssAdministrator_fv-az48_2019-05-22_04_51_17.trx' matches 'VSTest' test results format.
##[error]Dotnet command failed with non-zero exit code on the following projects : d:\a\1\s\src\StreamJsonRpc.Tests\StreamJsonRpc.Tests.csproj

As you can see it also emits a warning about the .trx file. None of this happens when I use the DotNetCoreInstaller@0 task. I wonder why in the world switching installer tasks would cause this problem.

[AArnott]

Awesome. Yes, I remember the task on OSX couldn’t accumulate, which really limited what I could do. I see in my Windows box at least that accumulation works. So I can complete my PR and we can close this issue. Thanks for your help.

[wli3]

It used to install different SDK versions in different location, so it cannot accumulate . And there was an bug for that. Looks like the install location is "C:\hostedtoolcache\windows\dotnet" without extra subfolder. It should be fixed