old_contents: import os
  import tee
  
  
  class Process(object):
      """Process related functions using the tee module (mostly)."""
  
      def __init__(self, quiet=False, env=None):
          self.quiet = quiet
          self.env = env
  
      def popen(self, cmd, echo=True, echo2=True):
          if self.quiet:
              echo = echo2 = False
          return tee.popen(cmd, echo, echo2, env=self.env)
  
      def pipe(self, cmd):
          rc, lines = self.popen(cmd, echo=False)
          if rc == 0 and lines:
              return lines[0]
          return ''
  
      def system(self, cmd):
          rc, lines = self.popen(cmd, echo=tee.NotEmpty())
          return rc
  
      def os_system(self, cmd):
          if self.quiet:
              cmd = cmd + ' >%s 2>&1' % os.devnull
          if self.env:
              cmd = ''.join('%s=%s ' % (k, v) for k, v in self.env.items()) + cmd
          return os.system(cmd)
  
  
new_contents: import os
  import tee
  
  
  class Process(object):
      """Process related functions using the tee module (mostly)."""
  
      def __init__(self, quiet=False, env=None):
          self.quiet = quiet
          self.env = env
  
      def popen(self, cmd, echo=True, echo2=True):
          if self.quiet:
              echo = echo2 = False
          return tee.popen(cmd, echo, echo2, env=self.env)
  
      def pipe(self, cmd):
          rc, lines = self.popen(cmd, echo=False)
          if rc == 0 and lines:
              return lines[0]
          return ''
  
      def system(self, cmd):
          rc, lines = self.popen(cmd)
          return rc
  
      def os_system(self, cmd):
          if self.quiet:
              cmd = cmd + ' >%s 2>&1' % os.devnull
          if self.env:
              cmd = ''.join('%s=%s ' % (k, v) for k, v in self.env.items()) + cmd
          return os.system(cmd)
  
  
subject: Remove NotEmpty filter from Process.system.