flushing stdout with v 1.4.0

[wannaknowmo]

hi,

first, i want to tell u how much we are appreciating the walter program.
we are using it mainly to go around some missing features in docker compose v3.
would it be possible to flush the stdout of walter version 1.4.0 ?

getting the following error

github.com/walter-cd/walter/stages.(*CommandStage).runCommand(0xc8201b70e0, 0x1)
/Users/takahi-i/work/walter/gopath/src/github.com/walter-cd/walter/stages/command_stage.go:263 +0x3d4
github.com/walter-cd/walter/stages.(*CommandStage).Run(0xc8201b70e0, 0x7f3046c765f8)
/Users/takahi-i/work/walter/gopath/src/github.com/walter-cd/walter/stages/command_stage.go:229 +0x144
github.com/walter-cd/walter/engine.(*Engine).executeStage(0xc820153880, 0x7f3046c765f8, 0xc8201b70e0, 0xc8201524e0, 0x1, 0x1, 0xc8209b2fc0, 0x0, 0x0, 0x0, ...)
/Users/takahi-i/work/walter/gopath/src/github.com/walter-cd/walter/engine/engine.go:117 +0x73a
github.com/walter-cd/walter/engine.(*Engine).ExecuteStage(0xc820153880, 0x7f3046c765f8, 0xc8201b70e0)
/Users/takahi-i/work/walter/gopath/src/github.com/walter-cd/walter/engine/engine.go:96 +0x563
github.com/walter-cd/walter/engine.(*Engine).executeAllChildStages.func1(0xc820153880, 0xc820074138)
/Users/takahi-i/work/walter/gopath/src/github.com/walter-cd/walter/engine/engine.go:154 +0x81
created by github.com/walter-cd/walter/engine.(*Engine).executeAllChildStages
/Users/takahi-i/work/walter/gopath/src/github.com/walter-cd/walter/engine/engine.go:155 +0x27d