Comment 1 for bug 1829779

I have an update on this. Eric and myself attempted to zero in the
exact cause. A few things we discovered:

 1) It has nothing to do with having a kernel running
 2) It has to do with having a chardev that is a server socket. This
    test produces command line arguments such as:

   -chardev socket,id=console,path=<path>.sock,server,nowait \
   -serial chardev:console

 3) It doesn't seem to have a connection to the test infrastructure code
    (python/qemu/qmp/*), as a I made a number of experiments which
    yielded no differences in behavior.

So, the reproducer given at:

 https://github.com/clebergnu/qemu/commit/c778e28c24030c4a36548b714293b319f4bf18df

Continues to be be valid (and continues to be limited to arm and aarch64).
Now, after a number of experiments, the following was found to be a 100%
reproducible *workaround*:

 https://github.com/clebergnu/qemu/commit/e1713f3b91972ad57c089f276c54db3f3fa63423

That basically shutdowns the *console* socket before proceeding with further QMP
interaction. The effectiveness of the workaround can be seen here:

 aarch64 command line:
  - https://travis-ci.org/clebergnu/qemu/jobs/535459499#L3633
 aarch64 QMP interaction:
  - https://travis-ci.org/clebergnu/qemu/jobs/535459499#L3663

 arm command line:
  - https://travis-ci.org/clebergnu/qemu/jobs/535459499#L3747
 arm QMP interaction:
  - https://travis-ci.org/clebergnu/qemu/jobs/535459499#L3767

I hope this provides a few more hints into the real issue.