Fix print out of warning if file of change index version is not a directory

The condition to print out the warning 'exists && !f.isDirectory()'
could never be true since 'exists' was only true if 'f.isDirectory()':
  boolean exists = f.exists() && f.isDirectory()

Change-Id: I93f7b140c05e43e5af4a3083f69e913ecf8f6a84
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>