O2checkcode/o2 systematic failure

Hi @dberzano,

The build/o2checkcode/o2 is failing all the time. Before these were python3 related problems

  File "/mnt/mesos/sandbox/sandbox/sw/slc7_x86-64/Python/v3.6.8-3/lib/python3.6/re.py", line 172, in match
    return _compile(pattern, flags).match(string)
TypeError: cannot use a string pattern on a bytes-like object
input queue has size 0
output queue has size 0

full details here. But now it even does not reach that point, since the unit test test_DetectorsBase_testMatBudLUT requiring o2sim does not find it:

sh: /mnt/mesos/sandbox/sandbox/sw/slc7_x86-64/O2/build_o2checkcode_o2-1/bin/o2sim: No such file or directory
Running 1 test case...
[INFO] Loading geometry FAIRGeom from ./O2geometry.root
Error in <TFile::TFile>: file ./O2geometry.root does not exist
[FATAL] Failed to open file ./O2geometry.root

Can this be fixed, please?