[fix] remove unused pipe in subprocess

For some reason this seems to be triggering a leak of a open file
descriptor, even though it should be garbage collected.

As for why it's there...well there was a time when I had hoped of
implementing support for stdin.
20 jobs for <span class="ref-name">minimize-zmq-threads</span> in 5 minutes and 34 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #18214
integration
containers.build

00:00:01

passed #18215
integration
libnrm.build

00:00:07

passed #18216
integration
nrm.build

00:00:05

 
  Test
failed #18286
integration
Hello.test

00:00:41

failed #18281
knl
KNL-Hello.test

00:00:41

passed #18221
knl
KNL-Listen.test

00:00:41

failed #18282
knl
KNL-Perfwrapper.test

00:00:41

passed #18217
knl
KNL-Power.test

00:00:42

failed #18283
knl
KNL-STREAM.test

00:00:41

passed #18220
integration
Listen.test

00:00:11

failed #18284
integration
Perfwrapper.test

00:00:10

passed #18225
rapl
py.test

00:01:04

failed #18280
integration
Hello.test

00:00:42

failed #18285
integration
Hello.test

00:00:10

failed #18222
integration
Hello.test

00:00:09

failed #18223
knl
KNL-Hello.test

00:00:41

failed #18219
knl
KNL-Perfwrapper.test

00:00:41

failed #18224
knl
KNL-STREAM.test

00:00:41

failed #18218
integration
Perfwrapper.test

00:00:11

 
  Style
skipped #18226
flake8
 
Name Stage Failure
failed
Hello.test Test
  )
]
Info: Processes started.
Info: Processes cancelled due to termination of: cmd run with exit information: Right (ExitSuccess,Clean,Clean)
Error: cmd run died before a message could be found with error code ExitSuccess
Uploading artifacts...
_output/*: found 6 matching files
Uploading artifacts to coordinator... ok id=18286 responseStatus=201 Created token=Mk1PA8Xf
ERROR: Job failed: exit status 1
failed
KNL-Hello.test Test
  )
]
Info: Processes started.
Info: Processes cancelled due to termination of: cmd run with exit information: Right (ExitSuccess,Clean,Clean)
Error: cmd run died before a message could be found with error code ExitSuccess
Uploading artifacts...
_output/*: found 6 matching files
Uploading artifacts to coordinator... ok id=18281 responseStatus=201 Created token=S4RwXYzC
ERROR: Job failed: exit status 1
failed
Perfwrapper.test Test
  )
]
Info: Processes started.
Info: Processes cancelled due to termination of: cmd run with exit information: Right (ExitSuccess,Clean,Clean)
Error: cmd run died before a message could be found with error code ExitSuccess
Uploading artifacts...
_output/*: found 8 matching files
Uploading artifacts to coordinator... ok id=18284 responseStatus=201 Created token=z9W9NyXi
ERROR: Job failed: exit status 1
failed
KNL-Perfwrapper.test Test
  )
]
Info: Processes started.
Info: Processes cancelled due to termination of: cmd run with exit information: Right (ExitSuccess,Clean,Clean)
Error: cmd run died before a message could be found with error code ExitSuccess
Uploading artifacts...
_output/*: found 8 matching files
Uploading artifacts to coordinator... ok id=18282 responseStatus=201 Created token=y8_BFxeS
ERROR: Job failed: exit status 1
failed
KNL-STREAM.test Test
Info: Cleaned the argo config.
Info: argo_nodeos_config successfully cleaned the container config.
[ daemon , cmd run , cmd listen (-f) progress ]
Info: Processes cancelled due to termination of: cmd run with exit information: Right (ExitSuccess,Clean,Clean)
Error: cmd run died before a message could be found with error code ExitSuccess
Uploading artifacts...
_output/*: found 8 matching files
Uploading artifacts to coordinator... ok id=18283 responseStatus=201 Created token=WHv4DgxM
ERROR: Job failed: exit status 1