Job #7841500 failed for 7595fea1:
It looks like one of the BundleUtilities tests writes to the source tree and can cause failures of CheckSourceTree, namely the file Tests/RunCMake/BundleUtilities/test.app/script.bat.
BundleUtilities
CheckSourceTree
Tests/RunCMake/BundleUtilities/test.app/script.bat
Cc: @kyle.edwards @brad.king