Readonly gridpack mode failed to generate loop-induced events

Dear Olivier,

I am working on the "readonly" gridpack mode to enable multithreading for event generation, as introduced in this launchpad:
https://answers.launchpad.net/mg5amcnlo/+question/662721

When I was testing this mode on a gridpack produced from the loop-induced process: "g g > z z [noborn=QCD]", using the latest version 2.7.2, an error occurs after executing ./run.sh [1].

The test gridpack is uploaded to [2] for your reference. Would you mind looking into this issue?

Many thanks,
Congqiao

[1]
Now generating 10 events with random seed 1 and granularity 1
WRITE GRIDCARD /data/pku/home/licq/L/process/madevent
Traceback (most recent call last):
  File "/data/pku/home/licq/L/process/madevent/bin/gridrun", line 86, in <module>
    cmd_line = cmd_interface.GridPackCmd(me_dir=root_path, nb_event=args[0], seed=args[1], gran=args[2])
  File "/data/pku/home/licq/L/process/madevent/bin/internal/madevent_interface.py", line 6385, in __init__
    self.launch(nb_event, seed)
  File "/data/pku/home/licq/L/process/madevent/bin/internal/madevent_interface.py", line 6480, in launch
    self.refine4grid(nb_event)
  File "/data/pku/home/licq/L/process/madevent/bin/internal/madevent_interface.py", line 6519, in refine4grid
    x_improve.launch() # create the ajob for the refinment and run those!
  File "/data/pku/home/licq/L/process/madevent/bin/internal/gen_ximprove.py", line 863, in launch
    self.get_job_for_event()
  File "/data/pku/home/licq/L/process/madevent/bin/internal/gen_ximprove.py", line 1732, in get_job_for_event
    self.check_events(goal_lum, to_refine, jobs, write_dir)
  File "/data/pku/home/licq/L/process/madevent/bin/internal/gen_ximprove.py", line 1747, in check_events
    new_results.read_results(pjoin(Sdir,P, 'G%s'%G, 'results.dat'))
  File "/data/pku/home/licq/L/process/madevent/bin/internal/sum_html.py", line 279, in read_results
    finput = open(filepath)
IOError: [Errno 2] No such file or directory: './P0_gg_zz/G1/results.dat'

[2] https://coli.web.cern.ch/coli/tmp/.200515-212529_mtbug/ggzz_noborn_272.tar.gz