make vi the default editor if no EDITOR

fixes #15577

docs/man/man1/ansible-vault.1.asciidoc.in

@@ -63,7 +63,7 @@ CREATE
 The *create* sub-command is used to initialize a new encrypted file.
 
 After providing a password, the tool will launch whatever editor you have defined
-with $EDITOR, and defaults to vim. Once you are done with the editor session, the
+with $EDITOR, and defaults to vi. Once you are done with the editor session, the
 file will be saved as encrypted data.
 
 The default cipher is AES (which is shared-secret based).

docsite/rst/playbooks_vault.rst

@@ -29,7 +29,7 @@ To create a new encrypted data file, run the following command::
 
 First you will be prompted for a password.  The password used with vault currently must be the same for all files you wish to use together at the same time.
 
-After providing a password, the tool will launch whatever editor you have defined with $EDITOR, and defaults to vim.  Once you are done with the editor session, the file will be saved as encrypted data.
+After providing a password, the tool will launch whatever editor you have defined with $EDITOR, and defaults to vi (before 2.1 the default was vim).  Once you are done with the editor session, the file will be saved as encrypted data.
 
 The default cipher is AES (which is shared-secret based).
 

lib/ansible/parsing/vault/__init__.py

@@ -445,7 +445,7 @@ class VaultEditor:
             os.chown(dest, prev.st_uid, prev.st_gid)
 
     def _editor_shell_command(self, filename):
-        EDITOR = os.environ.get('EDITOR','vim')
+        EDITOR = os.environ.get('EDITOR','vi')
         editor = shlex.split(EDITOR)
         editor.append(filename)