This makes the tests easier to copy and relocate to other test numbers without having to update content. Closes #6738
Classic MinGW / MSYS 1 doesn't support `MSYS2_ARG_CONV_EXCL`, so this test unnecessarily failed when using `file:/` instead of `file:///`. Closes https://github.com/curl/curl/pull/4554
Attempt to reproduce issue #3444. Closes #3447