Investigate why TestConfigServerExclusiveRootPools is broken on Windows / MacOS builds

[akerouanton]

• Related to Fix CI & tests #104
• TestConfigServerExclusiveRootPools: see

  go-connections/tlsconfig/config_test.go

  Lines 202 to 205 in 5cc4da5

  	if runtime.GOOS == "windows" || runtime.GOOS == "darwin" {
  	// FIXME: see https://github.com/docker/go-connections/issues/105.
  	t.Skip("FIXME: failing on Windows and darwin")
  	}

• TestConfigClientExclusiveRootPools: see

  go-connections/tlsconfig/config_test.go

  Lines 566 to 569 in 5cc4da5

  	if runtime.GOOS == "windows" || runtime.GOOS == "darwin" {
  	// FIXME: see https://github.com/docker/go-connections/issues/105.
  	t.Skip("FIXME: failing on Windows and darwin")
  	}

Both tests break with the following error:

Unable to verify certificate 1: x509: certificate signed by unknown authority

certificate 1 being systemRootTrustedCert:

go-connections/tlsconfig/config_test.go

Lines 20 to 41 in 5cc4da5

	systemRootTrustedCert = `
	-----BEGIN CERTIFICATE-----
	MIIDQTCCAimgAwIBAgITBmyfz5m/jAo54vB4ikPmljZbyjANBgkqhkiG9w0BAQsF
	ADA5MQswCQYDVQQGEwJVUzEPMA0GA1UEChMGQW1hem9uMRkwFwYDVQQDExBBbWF6
	b24gUm9vdCBDQSAxMB4XDTE1MDUyNjAwMDAwMFoXDTM4MDExNzAwMDAwMFowOTEL
	MAkGA1UEBhMCVVMxDzANBgNVBAoTBkFtYXpvbjEZMBcGA1UEAxMQQW1hem9uIFJv
	b3QgQ0EgMTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBALJ4gHHKeNXj
	ca9HgFB0fW7Y14h29Jlo91ghYPl0hAEvrAIthtOgQ3pOsqTQNroBvo3bSMgHFzZM
	9O6II8c+6zf1tRn4SWiw3te5djgdYZ6k/oI2peVKVuRF4fn9tBb6dNqcmzU5L/qw
	IFAGbHrQgLKm+a/sRxmPUDgH3KKHOVj4utWp+UhnMJbulHheb4mjUcAwhmahRWa6
	VOujw5H5SNz/0egwLX0tdHA114gk957EWW67c4cX8jJGKLhD+rcdqsq08p8kDi1L
	93FcXmn/6pUCyziKrlA4b9v7LWIbxcceVOF34GfID5yHI9Y/QCB/IIDEgEw+OyQm
	jgSubJrIqg0CAwEAAaNCMEAwDwYDVR0TAQH/BAUwAwEB/zAOBgNVHQ8BAf8EBAMC
	AYYwHQYDVR0OBBYEFIQYzIU07LwMlJQuCFmcx7IQTgoIMA0GCSqGSIb3DQEBCwUA
	A4IBAQCY8jdaQZChGsV2USggNiMOruYou6r4lK5IpDB/G/wkjUu0yKGX9rbxenDI
	U5PMCCjjmCXPI6T53iHTfIUJrU6adTrCC2qJeHZERxhlbI1Bjjt/msv0tadQ1wUs
	N+gDS63pYaACbvXy8MWy7Vu33PqUXHeeE6V/Uq2V8viTO96LXFvKWlJbYK8U90vv
	o/ufQJVtMVT8QtPHRh8jrdkPSHCa2XV4cdFyQzR1bldZwgJcJmApzyMZFo6IQ6XU
	5MsI+yMRQ+hDKXJioaldXgjUkK642M4UwtBV8ob2xJNDd2ZhwLnoQdeXeGADbkpy
	rqXRfboQnoZsG4q5WTP468SQvvG5
	-----END CERTIFICATE-----
	`

As noted in d5807de commit message:

The (*Certificate).Verify() method from crypto/x509 special-case
windows, darwin and ios GOOS to use a OS-specific verification process.
This process seems to consider root CAs as invalid for some unknown
reasons.

So either the syscall made by Verify() to retrieve the system-wide cert bundle return an empty set, it's out-of-date, or something else happen.