在Travis CI上使用Mono 5.14.0.177，msbuild 15.0，nuget 4.7.1构建失败，但在VirtualBox中无法重现

Question

对于Xenial和Trusty Ubuntu，我在Travis CI上使用Mono 5.14.0.177，msbuild 15.0，nuget 4.7.1进行构建失败，但在VirtualBox，Ubuntu Xenial中无法重现。

运行后：

mono tools/nuget/nuget.exe restore pythonnet.sln -o packages

错误消息是：

Currently running NuGet.exe 4.1.0.
Updating NuGet.exe to 4.7.1.
Update successful.
MSBuild auto-detection: using msbuild version '15.0' from '/usr/lib/mono/msbuild/15.0/bin'.
Error parsing solution file at /home/travis/build/pythonnet/pythonnet/pythonnet.sln: Invalid Image

这是VirtualBox的成功构建：

https://gist.github.com/denfromufa/23557331aba2ad548eba2fbff84f2307

并且在Travis CI中失败了：

https://travis-ci.org/pythonnet/pythonnet/jobs/419381040

关于GitHub的这个问题的更多细节：

https://github.com/pythonnet/pythonnet/pull/698

Answer 1

此问题已在pythonnet Travis CI中通过降级到msbuild 14.0暂时得到修复：

cmd = "{0} update -self".format(nuget)
self.debug_print("Updating NuGet: {0}".format(cmd))
subprocess.check_call(cmd, shell=use_shell)
cmd = "{0} restore pythonnet.sln  -MSBuildVersion 14 -o packages".format(nuget)

https://github.com/pythonnet/pythonnet/blob/master/setup.py#L332