veyron/runtimes/google/ipc: log the Recv error in TestDebugServer

May shed more light onto failure:
debug_test.go:116: call.Finish failed: ipc.Client:.panic: Bad protocol or type: failed to decode response: EOF

Change-Id: I1f4a7feb193faeeb59c8b13e5cecec95126a3fad
diff --git a/runtimes/google/ipc/debug_test.go b/runtimes/google/ipc/debug_test.go
index 4ddeee9..8b2cacf 100644
--- a/runtimes/google/ipc/debug_test.go
+++ b/runtimes/google/ipc/debug_test.go
@@ -1,6 +1,7 @@
 package ipc
 
 import (
+	"io"
 	"reflect"
 	"sort"
 	"testing"
@@ -108,6 +109,9 @@
 		for {
 			var me naming.VDLMountEntry
 			if err := call.Recv(&me); err != nil {
+				if err != io.EOF {
+					t.Fatalf("Recv failed for %q: %v. Results received thus far: %q", tc.name, err, results)
+				}
 				break
 			}
 			results = append(results, me.Name)