fix OSX issue in VSO build

also, make it possible to have more verbose build runs when needed

scripts/dotnet-cli-build/Utils/DotNetCli.cs

@@ -1,9 +1,8 @@
-using System.IO;
-using System.Linq;
-using System;
-using System.Runtime.InteropServices;
-using Microsoft.DotNet.Cli.Build.Framework;
+using Microsoft.DotNet.Cli.Build.Framework;
 using Microsoft.Extensions.PlatformAbstractions;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices;
 
 namespace Microsoft.DotNet.Cli.Build
 {
@@ -22,7 +21,15 @@ namespace Microsoft.DotNet.Cli.Build
 
         public Command Exec(string command, params string[] args)
         {
-            return Command.Create(Path.Combine(BinPath, $"dotnet{Constants.ExeSuffix}"), Enumerable.Concat(new[] { command }, args));
+            var newArgs = args.ToList();
+            newArgs.Insert(0, command);
+
+            if (EnvVars.Verbose)
+            {
+                newArgs.Insert(0, "-v");
+            }
+
+            return Command.Create(Path.Combine(BinPath, $"dotnet{Constants.ExeSuffix}"), newArgs);
         }
 
         public Command Restore(params string[] args) => Exec("restore", args);

scripts/dotnet-cli-build/Utils/EnvVars.cs

@@ -0,0 +1,32 @@
+using System;
+
+namespace Microsoft.DotNet.Cli.Build
+{
+    public class EnvVars
+    {
+        public static readonly bool Verbose = GetBool("DOTNET_BUILD_VERBOSE");
+
+        private static bool GetBool(string name, bool defaultValue = false)
+        {
+            var str = Environment.GetEnvironmentVariable(name);
+            if (string.IsNullOrEmpty(str))
+            {
+                return defaultValue;
+            }
+
+            switch (str.ToLowerInvariant())
+            {
+                case "true":
+                case "1":
+                case "yes":
+                    return true;
+                case "false":
+                case "0":
+                case "no":
+                    return false;
+                default:
+                    return defaultValue;
+            }
+        }
+    }
+}

scripts/dotnet-cli-build/project.json

@@ -10,7 +10,7 @@
     "System.Xml.XmlSerializer": "4.0.11-rc2-23924",
     "Microsoft.DotNet.Cli.Build.Framework": "1.0.0-*",
     "WindowsAzure.Storage": "6.2.2-preview",
-    "System.Reflection.Metadata": "1.2.0"
+    "System.Reflection.Metadata": "1.3.0-rc2-23924"
   },
   "frameworks": {
     "netstandardapp1.5": {