Don't call subprocess.Popen twice when output == 'file'.

This fixes the real issue behind https://github.com/nipy/nipype/issues/705
Don't call subprocess.Popen twice when output == 'file'.

This fixes the real issue behind https://github.com/nipy/nipype/issues/705
Merge branch 'master' of github.com:carlohamalainen/nipype

This is for 421601e8b9d3fd259061590a0ed6b962c466cd8c regarding
"Don't call subprocess.Popen twice when output == 'file'."
Merge pull request #789 from carlohamalainen/master

Don't call subprocess.Popen twice when output == 'file'.