spark_tests (master) segfaults intermittently

[navidR]

Reproduced on master, on different builds.

ctest --test-dir /home/navidr/dev/firo/build -R "^spark_tests$" --repeat until-fail:30 --output-
  on-failure

  Failure block (from master):

  /home/alef/dev/firo/src/test/spark_tests.cpp(274): Entering test case
  "connect_and_disconnect_block"
  Posix Signal: Segmentation fault
  Add debug information and then run:
  test_firo
  -printcrashinfo=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=

  Posix Signal: Segmentation fault
     0#: (0x592EE033C504) <unknown-file>       - ???
     1#: (0x7E56E5A45F60) libc_sigaction.c     - ???
     2#: (0x592EDFC65759) <unknown-file>       - ???
     3#: (0x592EDFE15AD1) <unknown-file>       - ???
     4#: (0x592EDFE15B10) <unknown-file>       - ???
     5#: (0x592EDFE22211) <unknown-file>       - ???
     6#: (0x592EDFE24820) <unknown-file>       - ???
     7#: (0x592EE0016EC7) <unknown-file>       - ???
     8#: (0x592EE00172F1) <unknown-file>       - ???
     9#: (0x592EE0028904) <unknown-file>       - ???
    10#: (0x592EE0029DB7) <unknown-file>       - ???
    11#: (0x592EE05AF59B) <unknown-file>       - ???
    12#: (0x7E56E5AA3D64) pthread_create.c:448 - start_thread
    13#: (0x7E56E5B373FC) clone3.S:80          - __clone3
  <end of output>
  Test time =   8.97 sec
  ----------------------------------------------------------
  Test Failed.
  "spark_tests" end time: Mar 15 19:05 GMT
  "spark_tests" time elapsed: 00:00:08
  ----------------------------------------------------------