Re-enable travis for Go tip

.travis.yml

@@ -1,6 +1,7 @@
 language: go
 
 go:
+  - tip
   - 1.3
   - 1.2
 

hack/test-go.sh

@@ -40,6 +40,11 @@ find_test_dirs() {
     \) -name '*_test.go' -print0 | xargs -0n1 dirname | sort -u | xargs -n1 printf "${KUBE_GO_PACKAGE}/%s\n"
 }
 
+# there is currently a race in the coverage code in tip.  Remove this when it is fixed
+# see https://code.google.com/p/go/issues/detail?id=8630 for details.
+if [[ ${TRAVIS_GO_VERSION} eq "tip" ]]; then
+  KUBE_COVER=""
+fi
 # -covermode=atomic becomes default with -race in Go >=1.3
 KUBE_COVER=${KUBE_COVER:--cover -covermode=atomic}
 KUBE_TIMEOUT=${KUBE_TIMEOUT:--timeout 30s}