3.6, Win10, VS recently reinstalled to 'Update 3'.  I believe these messages are somewhat new.

0:01:00 [111/402] test_distutils failed (env changed)
xxmodule.c
   Creating library C:\Users\Terry\AppData\Local\Temp\tmpbjffnmc3\Debug\Users\Terry\AppData\Local\Temp\tmpbjffnmc3\xx_d.cp36-win32.lib and object C:\Users\Terry\AppData\Local\Temp\tmpbjffnmc3\Debug\Users\Terry\AppData\Local\Temp\tmpbjffnmc3\xx_d.cp36-win32.exp
LINK : /LTCG specified but no code generation required; remove /LTCG from the link command line to improve linker performance
foo.c
   Creating library C:\Users\Terry\AppData\Local\Temp\tmp7302jrpo\tempt\Users\Terry\AppData\Local\Temp\tmp9132twos\foo_d.cp36-win32.lib and object C:\Users\Terry\AppData\Local\Temp\tmp7302jrpo\tempt\Users\Terry\AppData\Local\Temp\tmp9132twos\foo_d.cp36-win32.exp
LINK : /LTCG specified but no code generation required; remove /LTCG from the link command line to improve linker performance
foo.c
   Creating library C:\Users\Terry\AppData\Local\Temp\tmp7302jrpo\tempt\Users\Terry\AppData\Local\Temp\tmp9132twos\foo_d.cp36-win32.lib and object C:\Users\Terry\AppData\Local\Temp\tmp7302jrpo\tempt\Users\Terry\AppData\Local\Temp\tmp9132twos\foo_d.cp36-win32.exp
LINK : /LTCG specified but no code generation required; remove /LTCG from the link command line to improve linker performance
xxmodule.c
   Creating library C:\Users\Terry\AppData\Local\Temp\tmp9hq4ci8e\Debug\Users\Terry\AppData\Local\Temp\tmp9hq4ci8e\xx_d.cp36-win32.lib and object C:\Users\Terry\AppData\Local\Temp\tmp9hq4ci8e\Debug\Users\Terry\AppData\Local\Temp\tmp9hq4ci8e\xx_d.cp36-win32.exp
LINK : /LTCG specified but no code generation required; remove /LTCG from the link command line to improve linker performance
foo.c
   Creating library C:\Users\Terry\AppData\Local\Temp\tmp3qv0ulce\tempt\Users\Terry\AppData\Local\Temp\tmph1jy_aqh\foo_d.cp36-win32.lib and object C:\Users\Terry\AppData\Local\Temp\tmp3qv0ulce\tempt\Users\Terry\AppData\Local\Temp\tmph1jy_aqh\foo_d.cp36-win32.exp
LINK : /LTCG specified but no code generation required; remove /LTCG from the link command line to improve linker performance
foo.c
   Creating library C:\Users\Terry\AppData\Local\Temp\tmp3qv0ulce\tempt\Users\Terry\AppData\Local\Temp\tmph1jy_aqh\foo_d.cp36-win32.lib and object C:\Users\Terry\AppData\Local\Temp\tmp3qv0ulce\tempt\Users\Terry\AppData\Local\Temp\tmph1jy_aqh\foo_d.cp36-win32.exp
LINK : /LTCG specified but no code generation required; remove /LTCG from the link command line to improve linker performance
xxmodule.c
   Creating library build\temp.win32-3.6-pydebug\Debug\xx_d.cp36-win32.lib and object build\temp.win32-3.6-pydebug\Debug\xx_d.cp36-win32.exp
LINK : /LTCG specified but no code generation required; remove /LTCG from the link command line to improve linker performance

F:\Python\dev\36\build\test_python_3596>exit 1

F:\Python\dev\36\build\test_python_3596>exit 0
Warning -- files was modified by test_distutils