Ensure SSH key ends with newline

In at least some versions of the 'ssh-add' command, adding a SSH key
requires that SSH key is newline terminated. If it is not, ssh-add
doesn't add the key and, instead, unhelpfully prompts for a
passphrase for the key ('Enter passphrase for (stdin):').

This change makes sure the key is terminated with a newline character to
hopefully avoid this issue occurring as often.

Signed-off-by: Sam Lewis <sam.vr.lewis@gmail.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

kas/libkas.py

@@ -269,6 +269,11 @@ def ssh_add_key(env, key):
     """
         Adds an ssh key to the ssh-agent
     """
+    # The ssh-agent needs the key to end with a newline, otherwise it
+    # unhelpfully prompts for a password
+    if not key.endswith('\n'):
+        key += '\n'
+
     process = Popen(['ssh-add', '-'], stdin=PIPE, stdout=None,
                     stderr=PIPE, env=env)
     (_, error) = process.communicate(input=str.encode(key))