pipe of 7z.exe command fails

[jwmurray]

When I run an unpack command:

housing_tgz = BinDeps.unpack_cmd(tgz_path, housing_path, ".tgz", ""), the pipeline command at line 122:

  return pipeline(`$exe7z x $file -y -so`, `$exe7z x -si -y -ttar -o$directory`)

fails to execute, unless run(...) is imposed around the pipeline() call.

Environment: windows 10, Julia 1.1.1

here are a few executions from the REPL:

This one prints out the commands, but fails to unzip/untar:

julia> housing_tgz = BinDeps.unpack_cmd("C:\python\handson-ml2\datasets\housing\housing.tgz",
"C:\python\handson-ml2\datasets\housing\housing", ".tgz", "")
pipeline('c:\programs\julia\bin\7z.exe' x 'C:\python\handson-ml2\datasets\housing\housing.tgz' -y -so, stdout='c:\programs\julia\bin\7z.exe' x -si -y -ttar '-oC:\python\handson-ml2\datasets\housing\housing')

This one succeeds in unzipping and untarring:
julia> run(pipeline('c:\programs\julia\bin\7z.exe' x 'C:\python\handson-ml2\datasets\housing\housing.tgz' -y -so, stdout='c:\programs\julia\bin\7z.exe' x -si -y -ttar '-oC:\python\handson-ml2\datasets\housing\housing'))

7-Zip 18.05 (x64) : Copyright (c) 1999-2018 Igor Pavlov : 2018-04-30

Extracting archive:
'--
Path =
Type = tar
Code Page = UTF-8

Everything is Ok

Size: 1423529
Compressed: 9728
Base.ProcessChain(Base.Process[Process('c:\programs\julia\bin\7z.exe' x 'C:\python\handson-ml2\datasets\housing\housing.tgz' -y -so, ProcessExited(0)), Process('c:\programs\julia\bin\7z.exe' x -si -y -ttar '-oC:\python\handson-ml2\datasets\housing\housing', ProcessExited(0))], Base.DevNull(), Base.DevNull(), Base.DevNull())

julia>