Squish: Fix handling of shared folders

If the respective option is omitted we should not
use all python files of the current working directory
as this may lead to bad side effects.

Change-Id: I23d3c97971e40ecbc4c585b7fd12b58953b0f623
Reviewed-by: Robert Loehning <robert.loehning@qt.io>

tests/system/tools/findUnusedObjects.py

@@ -59,7 +59,11 @@ def parseCommandLine():
         sys.exit(1)
     onlyRemovable = options.onlyRemovable
     deleteObjects = options.delete
-    sharedFolders = map(os.path.abspath, options.sharedFolders.split(','))
+    if len(options.sharedFolders) == 0:
+        sharedFolders = ()
+    else:
+        sharedFolders = map(os.path.abspath, options.sharedFolders.split(','))
+
 
 def collectObjects():
     global objMap