We've disabled luajittex when building the binaries, so lets prevent texlive from trying to generate formats for it.
---- src/texlive-20170524-texmf/texmf-dist/web2c/fmtutil.cnf 2016-05-15 01:17:09.000000000 +0000
+--- src/texlive-20180414-texmf/texmf-dist/web2c/fmtutil.cnf 2016-05-15 01:17:09.000000000 +0000
+++ ../fmtutil.cnf 2017-05-31 05:20:32.516130878 +0000
@@ -82,7 +82,7 @@
# from luatex: