Remove unused imports

lib/pace/Install.py

@@ -6,7 +6,7 @@ used to automate the steps described in the README file in this dir
 """
 
 from __future__ import print_function
-import sys, os, subprocess, shutil
+import sys, subprocess
 from argparse import ArgumentParser
 
 sys.path.append('..')
@@ -102,4 +102,4 @@ if buildflag:
 
   print("Removing pace build files and archive ...")
   cmd = 'rm %s; make clean-build' % (download_filename)
-  subprocess.check_output(cmd, stderr=subprocess.STDOUT, shell=True)
+  subprocess.check_output(cmd, stderr=subprocess.STDOUT, shell=True)