Fix bazel-skylib with Bazel@HEAD (#462)

tests/analysis_test_test.sh

@@ -56,6 +56,21 @@ EOF
   mkdir -p rules
   cat > rules/BUILD <<EOF
 exports_files(["*.bzl"])
+EOF
+
+  mkdir -p lib
+  cat > lib/BUILD <<EOF
+exports_files(["*.bzl"])
+EOF
+  cat > lib/types.bzl <<EOF
+_a_tuple_type = type(())
+
+def _is_tuple(v):
+    return type(v) == _a_tuple_type
+
+types = struct(
+    is_tuple = _is_tuple,
+)
 EOF
 
   ln -sf "$(rlocation $TEST_WORKSPACE/rules/analysis_test.bzl)" rules/analysis_test.bzl