[CMake] Strange behavior with Nightly builds

[NoRulez]

I think i fond the problem, but I don't know how to solve it.

I have the following defined in the CTestScript.cmake:
if(${NEED_REPOSITORY_CHECKOUT})
    set(CTEST_CHECKOUT_COMMAND "${CTEST_UPDATE_COMMAND} co ${REPOSITORY_URL} \"${CTEST_SOURCE_DIRECTORY}\" -r HEAD")
else()
    set(CTEST_CHECKOUT_COMMAND "${CTEST_UPDATE_COMMAND} update")
endif()

which seems to be correct, but in CDash the update command looks like:
Update Command: "C:/Program Files/Subversion/bin/svn.exe" "update" "--non-interactive" "-r{2012-06-12 23:00:00 +0000}"