竞速检测器：如何在Windows上设置log_path？

I am using the Go race detector on Windows and would like the detected races to be logged to a file rather than to stderr. This is possible by setting the GORACE environment variable:

$ GORACE='log_path=/var/reports/myprogram' ./myprogram

However, when trying it on Windows my program writes an error to stderr and immediately exits:

PS C:\foo> $env:GORACE = 'log_path=C:\RaceReports\myprogram'
PS C:\foo> .\myprogram.exe
ERROR: expected '='
PS C:\foo>

It works fine if I don't use absolute paths:

PS C:\foo> $env:GORACE = 'log_path=myprogram'
PS C:\foo> .\myprogram.exe
PS C:\foo> ls


    Directory: C:\foo


Mode                LastWriteTime         Length Name
----                -------------         ------ ----
-a----       15/11/2017     17:17            581 myprogram.7904
-a----       15/11/2017     16:55        2599936 myprogram.exe


PS C:\foo>

Am I doing something wrong? Is this a bug in Go? Any help is much appreciated.