As of go1.13, test flags like test.timeout are registered lazily.
This means they are not available in package init() methods:
> Testing flags are now registered in the new Init function,
> which is invoked by the generated main function for the test.
> As a result, testing flags are now only registered when running
> a test binary, and packages that call flag.Parse during package
> initialization may cause tests to fail.
This moves the copy of CLI flags into TestMain, just prior to parse.
00e1ffb4e0