Auto merge of #56017 - alexcrichton:debug-test, r=alexcrichton
Auto merge of #56017 - alexcrichton:debug-test, r=alexcrichton

std: Add debugging for a failing test on appveyor

I'm not sure why this is failing, so let's hopefully get some more
information to help investigation!

GBGamer/rust,GBGamer/rust,graydon/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,graydon/rust,aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,aidancully/rust