Wow, couldn’t think that the source code tree was being ‘modified’ during the build. Indeed cloning again from git helped. The build now ‘almost’ completed, it only failed at 99%:
[100%] Building CXX object pcbnew/CMakeFiles/pcbnew_kiface_objects.dir/specctra_import_export/specctra_keywords.cpp.o
/opt/kicad/pcbnew/python/scripting/pcb_scripting_tool.cpp: In member function ‘virtual bool SCRIPTING_TOOL::Init()’:
/opt/kicad/pcbnew/python/scripting/pcb_scripting_tool.cpp:60:34: error: ‘PyImport_GetModule’ was not declared in this scope
if( PyObject* existing_mod = PyImport_GetModule( mod_name ) )
^~~~~~~~~~~~~~~~~~
/opt/kicad/pcbnew/python/scripting/pcb_scripting_tool.cpp:60:34: note: suggested alternative: ‘PyImport_AddModule’
if( PyObject* existing_mod = PyImport_GetModule( mod_name ) )
^~~~~~~~~~~~~~~~~~
PyImport_AddModule
pcbnew/CMakeFiles/pcbnew_kiface_objects.dir/build.make:4069: recipe for target 'pcbnew/CMakeFiles/pcbnew_kiface_objects.dir/python/scripting/pcb_scripting_tool.cpp.o' failed
make[2]: *** [pcbnew/CMakeFiles/pcbnew_kiface_objects.dir/python/scripting/pcb_scripting_tool.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
CMakeFiles/Makefile2:2304: recipe for target 'pcbnew/CMakeFiles/pcbnew_kiface_objects.dir/all' failed
make[1]: *** [pcbnew/CMakeFiles/pcbnew_kiface_objects.dir/all] Error 2
Makefile:165: recipe for target 'all' failed
make: *** [all] Error 2
12:36:03: The process "/snap/bin/cmake" exited with code 2.
Error while building/deploying project kicad (kit: Desktop)
When executing step "Build"
It looks like this function is only available in Python 3.7, not in 3.6. I reported it here https://gitlab.com/kicad/code/kicad/-/issues/8554
If I comment out a couple of lines in that cpp file, the build finally succeeds. Thanks for all the help!