win-vs2015 build failures

[Trott]

win-vs2015 builds have been failing a fair amount. When that happens, the fanned jobs don't run and there are no tests for Windows. So the CI has to be run again.

It's not a crisis right now, but it seems to me to be the biggest single infrastructure-related issue with CI and it would be great if there was a solution.

Here are some sample builds that show the issue I'm talking about:

• build 1451
• build 1441
• build 1432
• build 1409

[joaocgreis]

First time this happened in CI was February 1, was very rare but seems to be becoming more frequent.

Ref nodejs/node#5224 , the environment should be the same for every build, I'll double check. EDIT: it is.

[orangemocha]

Investigating...

[joaocgreis]

For reference, here's the error: c:\workspace\node-compile-windows\label\win-vs2015\deps\openssl\openssl.targets(28,5): error MSB4175: The task factory "XamlTaskFactory" could not be loaded from the assembly "Microsoft.Build.Tasks.Core". Could not find file 'C:\Users\Administrator\AppData\Local\Temp\1\3jvoaqze.dll'. [c:\workspace\node-compile-windows\label\win-vs2015\deps\openssl\openssl.vcxproj]

Last time this happened on CI was on March 2. Chakracore builds were reproducing this very frequently, but now are all green too. So this might be fixed, one suspect is Windows update.

I wasn't able to understand the root cause of this, but seems to be related with the Temp folder. Possible things to try if we ever get a consistent repro is to clean the Temp folder before the runs or using a different folder by setting the environment variables that point to it.

[orangemocha]

We did some investigation, but so far it hasn't been conclusive. Given that this hasn't happened any more since March 2nd, I think we should abandon the investigation for now and resume it only if the problem reappears.