TeamCity Build step failed- the error was:
[Step 5/7] Host key verification failed.
[Step 5/7] Host key verification failed.
[Step 5/7] fatal: The remote end hung up unexpectedly
To fix this you should run the next command on build agent:
git ls-remote -h ssh://git@URL_OF_STASH/PATH_TO_FILE.git
and type yes to add your stash server to known hosts.