Unable to build examples (Python 3.8)

Summary

Cannot build examples

Steps to reproduce

Using pip stable release:

$ bst --version
1.4.1
$ cd doc/examples/flatpak-autotools
$ bst build hello.bst
[--:--:--][][] STATUS  Cache usage recomputed: 125.2M / infinity (0%)
[--:--:--][][] START   Build
[--:--:--][][] START   Loading elements
[00:00:00][][] SUCCESS Loading elements
[--:--:--][][] START   Resolving elements
[00:00:00][][] SUCCESS Resolving elements
[--:--:--][][] START   Resolving cached state
[00:00:00][][] SUCCESS Resolving cached state
[--:--:--][][] START   Checking sources
[00:00:00][][] SUCCESS Checking sources
 
BuildStream Version 1.4.1
  Session Start: Wednesday, 11-12-2019 at 19:15:17
  Project:       flatpak-autotools (/home/alberto/projects/python/buildstream/doc/examples/flatpak-autotools)
  Targets:       hello.bst
  Cache Usage:   125.2M / infinity (0%)
 
User Configuration
  Configuration File:      /home/alberto/.config/buildstream.conf
  Log Files:               /home/alberto/.cache/buildstream/logs
  Source Mirrors:          /home/alberto/.cache/buildstream/sources
  Build Area:              /home/alberto/.cache/buildstream/build
  Artifact Cache:          /home/alberto/.cache/buildstream/artifacts
  Strict Build Plan:       Yes
  Maximum Fetch Tasks:     10
  Maximum Build Tasks:     2
  Maximum Push Tasks:      4
  Maximum Network Retries: 2
 
Project Options
  arch: x86_64
 
Pipeline
fetch needed 1fb677ea63be533ff4391db8c764030a80500c8f1feba0959eb747f720fd3748 base/sdk.bst
     waiting 6fbcd70444b9b3bb74e48bf930fd93a0715e854bfe370c4a43b7e9d2d81caee7 base/usrmerge.bst
     waiting 60ef22ffacf88b1fb99d3bf72752456b55c83ec86672310bcf7917f55ed7d485 base.bst
     waiting 8c609e7d39e81c68c2f8162a19440d8a947f1b95535dfb18d43b7fbef611866f hello.bst
===============================================================================
[--:--:--][][] BUG     no running event loop
 
    Traceback (most recent call last):
      File "/usr/bin/bst", line 8, in <module>
        sys.exit(cli())
      File "/usr/lib/python3.8/site-packages/click/core.py", line 764, in __call__
        return self.main(*args, **kwargs)
      File "/usr/lib/python3.8/site-packages/buildstream/_frontend/cli.py", line 173, in override_main
        original_main(self, args=args, prog_name=prog_name, complete_var=None,
      File "/usr/lib/python3.8/site-packages/click/core.py", line 717, in main
        rv = self.invoke(ctx)
      File "/usr/lib/python3.8/site-packages/click/core.py", line 1137, in invoke
        return _process_result(sub_ctx.command.invoke(sub_ctx))
      File "/usr/lib/python3.8/site-packages/click/core.py", line 956, in invoke
        return ctx.invoke(self.callback, **ctx.params)
      File "/usr/lib/python3.8/site-packages/click/core.py", line 555, in invoke
        return callback(*args, **kwargs)
      File "/usr/lib/python3.8/site-packages/click/decorators.py", line 27, in new_func
        return f(get_current_context().obj, *args, **kwargs)
      File "/usr/lib/python3.8/site-packages/buildstream/_frontend/cli.py", line 340, in build
        app.stream.build(elements,
      File "/usr/lib/python3.8/site-packages/buildstream/_stream.py", line 211, in build
        self._run()
      File "/usr/lib/python3.8/site-packages/buildstream/_stream.py", line 1022, in _run
        _, status = self._scheduler.run(self.queues)
      File "/usr/lib/python3.8/site-packages/buildstream/_scheduler/scheduler.py", line 153, in run
        self._sched()
      File "/usr/lib/python3.8/site-packages/buildstream/_scheduler/scheduler.py", line 427, in _sched
        self._sched_queue_jobs()
      File "/usr/lib/python3.8/site-packages/buildstream/_scheduler/scheduler.py", line 401, in _sched_queue_jobs
        self._spawn_job(job)
      File "/usr/lib/python3.8/site-packages/buildstream/_scheduler/scheduler.py", line 281, in _spawn_job
        job.spawn()
      File "/usr/lib/python3.8/site-packages/buildstream/_scheduler/jobs/job.py", line 162, in spawn
        self._watcher.add_child_handler(self._process.pid, self._parent_child_completed)
      File "/usr/lib/python3.8/asyncio/unix_events.py", line 1286, in add_child_handler
        loop = events.get_running_loop()
    RuntimeError: no running event loop

Trying with master:

$ cd buildstream
$ sudo pip3 install -e .
$ bst --version
1.91.2+286.ga8fb5cd7
 
cd doc/examples/autotools
$ bst build hello.bst
 
Error loading user configuration: /home/alberto/projects/python/buildstream/src/buildstream/data/userconfig.yaml: Severely malformed YAML:
 
'NoneType' object is not callable

What is the current bug behavior?

build fails on 1.4.1 and master

What is the expected correct behavior?

be able to build examples

Relevant logs and/or screenshots

Anything else is needed?

Possible fixes

Other relevant information

Edited by Jürg Billeter