message: test: use pgrep for better compatibility
  pidof is not available on BSD system, while pgrep is present on BSD, Linux and macOS
diff: @@ -394,11 +394,12 @@ def run_tests(*, test_list, src_dir, build_dir, tmpdir, jobs=1, enable_coverage=
  args = args or []
  # Warn if peercoind is already running
  - # pidof might fail or return an empty string if bitcoind is not running
  try:
  - if subprocess.check_output(["pidof", "peercoind"]) not in [b'']:
  + # pgrep exits with code zero when one or more matching processes found
  + if subprocess.run(["pgrep", "-x", "peercoind"], stdout=subprocess.DEVNULL).returncode == 0:
  print("%sWARNING!%s There is already a peercoind process running on this system. Tests may fail unexpectedly due to resource contention!" % (BOLD[1], BOLD[0]))
  - except (OSError, subprocess.SubprocessError):
  + except OSError:
  + # pgrep not supported
  pass
  # Warn if there is a cache directory
  