Do not fail for legacy rdb that only contains root key
diff --git a/cppuhelper/source/defaultbootstrap.cxx b/cppuhelper/source/defaultbootstrap.cxx
index 4921011..a11f220 100644
--- a/cppuhelper/source/defaultbootstrap.cxx
+++ b/cppuhelper/source/defaultbootstrap.cxx
@@ -1318,7 +1318,12 @@ bool ServiceManager::readLegacyRdbFile(rtl::OUString const & uri) {
            static_cast< cppu::OWeakObject * >(this));
    }
    RegistryKeyArray impls;
    if (rootKey.openSubKeys("IMPLEMENTATIONS", impls) != REG_NO_ERROR) {
    switch (rootKey.openSubKeys("IMPLEMENTATIONS", impls)) {
    case REG_NO_ERROR:
        break;
    case REG_KEY_NOT_EXISTS:
        return true;
    default:
        throw css::uno::DeploymentException(
            "Failure reading legacy rdb file " + uri,
            static_cast< cppu::OWeakObject * >(this));