Node.JS Child Process exec strange behaviour

When I execute a command in terminal it lasts ~5s, but when I use require('child_process').exec with a 1 minute timeout it returns [Error: Command failed: ] killed: true, code: null, signal: 'SIGTERM' after 1 minute?

P.S. that command generates some files and in both cases the output is ok.

Update: example of such behaviour:

var exec = require('child_process').exec
exec('docker run --rm -i ubuntu sleep 1',
  {timeout:15000},
  function(){
    console.log(arguments)
  }
)