ansible-vault: missing editor message unclear

Issue Type:

Bug Report

Ansible Version:

ansible 1.8.2
  configured module search path = None

Environment:

Running Ubuntu 14.04.1 LTS.

Summary:

When ansible-vault invokes an editor, for example when creating a new file,
and that editor is not found,
the message presented is unclear about exactly what is going on.

Steps To Reproduce:

1. run: EDITOR=testing ansible-vault create test
   

   Expected Results:

I expected ansible-vault to give me a bit more information to what was happening. For example, something like:

ERROR: Failed to launch editor: [Errno 2] No such file or directory

Maybe even what editor it was trying to launch.

Actual Results:

tyler@ubuntu:~$ EDITOR=testing ansible-vault create test
Vault password:
Confirm Vault password:
ERROR: [Errno 2] No such file or directory