[MacPorts] #72225: system "cargo <opts>" leads to `sh` zombie when `cargo` fails or is interrupted

[MacPorts]

#72225: system "cargo <opts>" leads to `sh` zombie when `cargo` fails or is
interrupted
---------------------+--------------------
  Reporter:  RJVB    |      Owner:  (none)
      Type:  defect  |     Status:  new
  Priority:  Normal  |  Milestone:
 Component:  base    |    Version:
Resolution:          |   Keywords:
      Port:          |
---------------------+--------------------

Comment (by RJVB):

 Actually, it can clearly also happen when `cargo` does finish
 successfully:

 ```
     Finished `release` profile [optimized] target(s) in 6m 10s
 ```

 yet

 ```
 > ps -axlww | fgrep 95538
   505 95538 94381     4006   0  14 19  2507756  38528 -      SN+
 0 ttys006    0:03.04 /opt/local/libexec/macports/bin/tclsh8.5
 /opt/local/bin/port -nok -d build rustup +cpucompat+rustup_build
 configure.optflags=-Os -ftree-vectorize configure.compiler=macports-
 clang-9.0 configureccache=yes
   505 95558 95538     6006   0   0 19        0      0 -      ZN+
 0 ttys006    0:00.00 (sh)
 ```

-- 
Ticket URL: <https://trac.macports.org/ticket/72225#comment:1>
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