Hi!
I just noticed this (in ~/src/C/iotwatch.lib): % git submodule add ../Git/threadtools.git threadtools
complained: fatal: repository '~/src/C/Git/Git/threadtools.git' does not exist
"~" is not actually displayed here, but that does not matter: Just image it reads "/home/user" instead.
Using the absolute path, worked, however. % git submodule add ~/src/C/Git/threadtools.git threadtools
git version 2.26.2 from SLES12 SP5
Regards, Ulrich