Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -569,3 +569,8 @@
   endif()
 endif()
 
+if(CMAKE_GENERATOR MATCHES "Ninja")
+  add_custom_target(update
+      COMMAND find "${CMAKE_CURRENT_SOURCE_DIR}" -name .svn -type d | sed -e 's/\\.svn//' | xargs svn update
+  )
+endif()