Nerdbank.GitVersioning: MarshalDirectiveException on unices with 2.2.3

When I tried updating from 2.1.23 to 2.2.3 locally, I started seeing this failure repeated many times.

This does not reproduce on the same machine with a tiny repro project, only in the MSBuild repo in our projects. I’ve reproduced on Ubuntu 18.04 (with SDK 2.1.300 and 2.1.401) and macOS 10.13 (just SDK 2.1.300), but it seems to work fine on .NET Core on Windows.

At the moment I suspect a CoreCLR bug rather than a problem with GitVersioning or LibGit2Sharp, but I wanted to file this for awareness in case it’s more widespread.

10:41:29.576  1:19>Target "GetBuildVersion: (TargetId:201)" in file "/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/Nerdbank.GitVersioning.targets" from project "/home/raines/src/msbuild/src/Framework/Microsoft.Build.Framework.csproj" (target "GenerateAssemblyVersionInfo" depends on it):
                   Using "Nerdbank.GitVersioning.Tasks.GetBuildVersion" task from assembly "/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/MSBuildCore/Nerdbank.GitVersioning.Tasks.dll".
                   Task "Nerdbank.GitVersioning.Tasks.GetBuildVersion" (TaskId:117)
                     Task Parameter:TargetsPath=/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/ (TaskId:117)
10:41:29.604  1:19>/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/Nerdbank.GitVersioning.targets(63,5): error MSB4018: The "Nerdbank.GitVersioning.Tasks.GetBuildVersion" task failed unexpectedly. [/home/raines/src/msbuild/src/Framework/Microsoft.Build.Framework.csproj]
/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/Nerdbank.GitVersioning.targets(63,5): error MSB4018: System.Runtime.InteropServices.MarshalDirectiveException: StrictFilePathMarshaler must be used on a FilePath. [/home/raines/src/msbuild/src/Framework/Microsoft.Build.Framework.csproj]
/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/Nerdbank.GitVersioning.targets(63,5): error MSB4018:    at LibGit2Sharp.Core.StrictFilePathMarshaler.MarshalManagedToNative(Object managedObj) [/home/raines/src/msbuild/src/Framework/Microsoft.Build.Framework.csproj]
/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/Nerdbank.GitVersioning.targets(63,5): error MSB4018:    at System.StubHelpers.MngdRefCustomMarshaler.ConvertContentsToNative(IntPtr pMarshalState, Object& pManagedHome, IntPtr pNativeHome) [/home/raines/src/msbuild/src/Framework/Microsoft.Build.Framework.csproj]
/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/Nerdbank.GitVersioning.targets(63,5): error MSB4018:    at LibGit2Sharp.Core.NativeMethods.git_repository_open(git_repository*& repository, FilePath path) [/home/raines/src/msbuild/src/Framework/Microsoft.Build.Framework.csproj]
/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/Nerdbank.GitVersioning.targets(63,5): error MSB4018:    at LibGit2Sharp.Core.Proxy.git_repository_open(String path) [/home/raines/src/msbuild/src/Framework/Microsoft.Build.Framework.csproj]
/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/Nerdbank.GitVersioning.targets(63,5): error MSB4018:    at LibGit2Sharp.Repository..ctor(String path, RepositoryOptions options, RepositoryRequiredParameter requiredParameter) [/home/raines/src/msbuild/src/Framework/Microsoft.Build.Framework.csproj]
/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/Nerdbank.GitVersioning.targets(63,5): error MSB4018:    at Nerdbank.GitVersioning.GitExtensions.OpenGitRepo(String pathUnderGitRepo) [/home/raines/src/msbuild/src/Framework/Microsoft.Build.Framework.csproj]
/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/Nerdbank.GitVersioning.targets(63,5): error MSB4018:    at Nerdbank.GitVersioning.VersionOracle.Create(String projectDirectory, String gitRepoDirectory, ICloudBuild cloudBuild, Nullable`1 overrideBuildNumberOffset, String projectPathRelativeToGitRepoRoot) [/home/raines/src/msbuild/src/Framework/Microsoft.Build.Framework.csproj]
/home/raines/.nuget/packages/nerdbank.gitversioning/2.2.3/build/Nerdbank.GitVersioning.targets(63,5): error MSB4018:    at Nerdbank.GitVersioning.Tasks.GetBuildVersion.ExecuteInner() [/home/raines/src/msbuild/src/Framework/Microsoft.Build.Framework.csproj]
                   Done executing task "Nerdbank.GitVersioning.Tasks.GetBuildVersion" -- FAILED. (TaskId:117)