.  uniq -c
  ^~~~
process_test.py:1: 'uniq' not found
pipe_status: [-1, -1, -1, 127]
.  head
  ^~~~
process_test.py:1: 'head' not found
  ls
  ^~
process_test.py:1: 'ls' not found
  head
  ^~~~
process_test.py:1: 'head' not found
  cat
  ^~~
process_test.py:1: 'cat' not found
  sort --reverse
  ^~~~
process_test.py:1: 'sort' not found
.Sat Jul 17 23:46:39 PDT 2021
date returned 0
F.
======================================================================
FAIL: testProcess (__main__.ProcessTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "core/process_test.py", line 112, in testProcess
    print(p.RunWait(self.waiter, why))
  File "/home/andy/git/oilshell/oil/core/process.py", line 940, in RunWait
    self.Start(why)
  File "/home/andy/git/oilshell/oil/core/process.py", line 880, in Start
    self.thunk.Run()
  File "/home/andy/git/oilshell/oil/core/process.py", line 677, in Run
    self.ext_prog.Exec(self.argv0_path, self.cmd_val, self.environ)
  File "/home/andy/git/oilshell/oil/core/process.py", line 563, in Exec
    self._Exec(argv0_path, cmd_val.argv, cmd_val.arg_spids[0], environ, True)
  File "/home/andy/git/oilshell/oil/core/process.py", line 606, in _Exec
    span_id=argv0_spid)
  File "/home/andy/git/oilshell/oil/core/ui.py", line 280, in Print_
    _PrintWithOptionalSpanId('', msg, span_id, self.arena)
  File "/home/andy/git/oilshell/oil/core/ui.py", line 188, in _PrintWithOptionalSpanId
    _PrintWithSpanId(prefix, msg, span_id, arena, f)
  File "/home/andy/git/oilshell/oil/core/ui.py", line 99, in _PrintWithSpanId
    line_span = arena.GetLineSpan(span_id)
  File "/home/andy/git/oilshell/oil/core/alloc.py", line 147, in GetLineSpan
    'Span ID out of range: %d is greater than %d' % (span_id, len(self.spans))
AssertionError: Span ID out of range: 0 is greater than 0

----------------------------------------------------------------------
Ran 5 tests in 0.009s

FAILED (failures=1)
('BEFORE', ['0', '1', '2', '3', '4'])
('AFTER', ['0', '1', '2', '3', '4'])
------------------------------------------------------------
ls | cut -d . -f 1 | head
[-1, -1, 127]
[-1, -1, -1, 127]
('FDS BEFORE', ['0', '1', '2', '3', '4'])
------------------------------------------------------------
date
------------------------------------------------------------
does-not-exist
..
----------------------------------------------------------------------
Ran 5 tests in 0.019s

OK
('BEFORE', ['0', '1', '2', '3', '4'])
('AFTER', ['0', '1', '2', '3', '4'])
------------------------------------------------------------
ls | cut -d . -f 1 | head
[-1, -1, 127]
[-1, -1, -1, 127]
('FDS BEFORE', ['0', '1', '2', '3', '4'])
------------------------------------------------------------
date
------------------------------------------------------------
does-not-exist
1
('FDS AFTER', ['0', '1', '2', '3', '4'])