We had some problems:
simultaneous compiling of kconfig in the same tree;
attempt to use menuconfig in some examples and ut in batch mode (w/o interactive console)
Also increase debug abilities in CI:
force non-interactive building;
add variable DEBUG_SHELL to toggle verbosity of scripts
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
