Now the tests do not pass
Before we had incorrect code of the error code checking
in build_examples.sh for that case and did nothing in test_build_system.sh.
The CI uses the mirror-submodule-update.sh for non-permanent reassignment
of 3rdparty sub-modules to local mirrors (only for 'non-master' branches).
List of the mirrors in mirror-list.txt
You can use the script locally to speed up data retrieval on network problems
check_submodule_sync job uses 'GIT_STRATEGY: clone' to check the availability of public sources