Found a simple expression that fails on OSX, in the latest TRE, but passes in ICU on OSX

[dhoerl]

This expression succeeds when it should fail:

ret = tre_regcomp(&trx, "^(?:(?:(?:(?:(?:[0-9]){1,4}):){0,4})(?:(?:[0-9]){1,4}))?::$", REG_EXTENDED | REG_NOSUB);
test = "1:2:3:4:5:6::";
ret = tre_regexec(&trx, test, 0, NULL, 0);