xunit smoke-test flaky: "The library 'libhostpolicy.so' required to execute the application was not found"

[dagood]

https://dev.azure.com/dnceng/internal/_build/results?buildId=715168&view=logs&j=e242d376-9fed-565d-2a2a-c4e65b5ab60e&t=a2b6a900-d726-529e-22d8-1a91fa385f64&l=253

This happened during tarball smoke-test in a fedora30 Offline Portable job:

starting language C#, type xunit
    running new
The template "xUnit Test Project" was created successfully.
    running restore
/tb/tarball_715168/testing-smoke/builtCli/sdk/3.1.106/MSBuild.dll -nologo -maxcpucount -target:Restore -verbosity:m /bl:/tb/tarball_715168/testing-smoke/C#_xunit_local_nohttps_restore.binlog ./C#_xunit.csproj
  Restore completed in 1.82 sec for /tb/tarball_715168/testing-smoke/C#_xunit/C#_xunit.csproj.
    running test
/tb/tarball_715168/testing-smoke/builtCli/sdk/3.1.106/MSBuild.dll -nologo -maxcpucount -nodereuse:false -restore -target:VSTest -verbosity:m -verbosity:quiet /bl:/tb/tarball_715168/testing-smoke/C#_xunit_local_nohttps_test.binlog ./C#_xunit.csproj
Test run for /tb/tarball_715168/testing-smoke/C#_xunit/bin/Debug/netcoreapp3.1/C#_xunit.dll(.NETCoreApp,Version=v3.1)
A fatal error was encountered. The library 'libhostpolicy.so' required to execute the application was not found in '/tb/tarball_715168/testing-smoke/builtCli/sdk/3.1.106/'.
Failed to run as a self-contained app. If this should be a framework-dependent app, add the /tb/tarball_715168/testing-smoke/builtCli/sdk/3.1.106/vstest.console.runtimeconfig.json file specifying the appropriate framework.

This may be difficult to diagnose without more artifacts (does the file actually not exist?): #1345 / #1321

[MichaelSimons]

Smoke-tests are now reliable. This issue is obsolete.