title: gcloud deploy does not upload new files
body: <p>I just stumbled on the following issue in App Engine Standard with a Python 2.7 enviroment</p>
  
  <p>So I deployed to my test environment yesterday and today I had the idea of updating one of my applications. I do my normal "gcloud deploy ... " and it says updating 3 files ... While I actually changed a bunch of files. Basically my deploy command says the files are not changed. </p>
  
  <p>After some searching around I found that files are being uploaded to a staging area and checked with a hash. Is it safe to actually clear this staging area, or does the gcloud command have some secret force option to actually force the files to be renewed. </p>
  
  <p>The gcloud command has not given any errors what so ever, nor was it aborted at some point of deployment or something. So I have no errors, but my files aren't uploaded at all. I also tried modifying alot of files, and nothing changed</p>
  
  <p>I never use the promote option for these rare cases that a deploy might fail</p>
  
  <p>So anyone encountered this before, or has a solution to this issue ?</p>