Temporary workaround to get artifacts downloading on old build agents until they are upgraded.

Author: UnityAlex

mcs/class/System/Mono.Btls/MonoBtlsProvider.cs

@@ -149,6 +149,12 @@ internal override bool ValidateCertificate (
 			X509CertificateCollection certificates, bool wantsChain, ref X509Chain chain,
 			ref SslPolicyErrors errors, ref int status11)
 		{
+			// Super ugly hack to make things work on Unity build servers
+			// FIXME: REMOVE THIS WHEN AGENTS RUN NEWER LINUX
+			if (Environment.OSVersion.Platform == PlatformID.Unix
+				&& Environment.GetEnvironmentVariable ("UNITY_THISISABUILDMACHINE") != null)
+				return true;
+
 			if (chain != null) {
 				var chainImpl = (X509ChainImplBtls)chain.Impl;
 				var success = chainImpl.StoreCtx.VerifyResult == 1;