Summary

When using git push --atomic, if the push is a failure case (e.g. local is behind origin) and the operation is over SSH, then the command hangs instead of returning control to the terminal

Steps to Reproduce

1. Create a new repository on Bitbucket, then clone and cd into the repo
2. Run the following commands to create some test commits and then make an atomic push that should fail:

   echo test >> test && git add . && git commit -m "test"
   echo test >> test && git add . && git commit -m "test"
   
   git push origin master
   
   git push --atomic origin HEAD~1:refs/heads/master
   

Expected Results

Upon failure, the session should close and control should be returned to the client

Actual Results

On Bitbucket Server, the command hangs indefinitely and requires a user interruption to exit:

➜  atomictest git:(master) git push --atomic origin HEAD~1:refs/heads/master
error: atomic push failed for ref refs/heads/master. status: 2

^CKilled by signal 2.