Only repack if there's src bits to repack.

- Unblocks tests on CI.

Author: N. Taylor Mullen

makefile.shade

@@ -15,8 +15,8 @@ var AUTHORS='Microsoft Open Technologies, Inc.'
 use-standard-lifecycle
 k-standard-goals
 
-#repack-x86 target='compile'
-    @{    
+#repack-x86 target='compile' if='Directory.Exists("src")'
+    @{
         if (string.IsNullOrEmpty(CONFIGURATION_LOCAL))
         {
             CONFIGURATION_LOCAL = "Debug";