To figure out the root of the JDK build, we set the TOPDIR variable in configure. Furthermore, we clean it up using UTIL_FIXUP_PATH as we do with all paths. On Windows, this can result in the path becoming all lowercase. Since Windows paths are case insensitive, this is normally not a problem. However, we try to strip the TOPDIR from paths in several locations like this:

$$(subst $$(TOPDIR)/, , $$($1_TEST_RESULTS_DIR))

and that will only work if the case actually matches.