[6.3][ML] Fix bug upgrading state from 5.6 direct to 6.3 causing SIGSEGV on open job#145

tveasey merged 3 commits intoelastic:6.3elastic/ml-cpp:6.3from

tveasey:port/143-to-6.3tveasey/ml-cpp-1:port/143-to-6.3Copy head branch name to clipboard