ExternalProject CONFIGURE_HANDLED_BY_BUILD test not robust
The CONFIGURE_HANDLED_BY_BUILD subtest of RunCMake.ExternalProject relies on
file(TIMESTAMP) to determine whether one file is newer than another. That command only has one second resolution, but that is not always enough. See the following example failure for a case where this can be seen:
The BUILD_COMMAND used in that test could be lengthened to sleep by more than 1 second, but that's not ideal. Can it be reworked to use a condition check implemented with
if(fileA IS_NEWER_THAN fileB) instead? That should be more robust, although there are still some file systems which apparently only have one second accuracy anyway, so maybe we just have to accept either a longer sleep or the occasional flakey false failures (not ideal).