<!--- Verify first that your issue is not already reported on GitHub -->
<!--- Also test if the latest release and devel branch are affected too -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
<!--- Explain the problem briefly below -->
When encrypting a single variable from sdtin the resulting output appears right after the value.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
`ansible/lib/ansible/cli/vault.py`

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible --version
ansible 2.9.1
  config file = /Users/alexandrechouinard/.ansible.cfg
  configured module search path = ['/Users/alexandrechouinard/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /Users/alexandrechouinard/workspace/repos/ops2.0/provisioning-prometheus-vm/venv/lib/python3.7/site-packages/ansible
  executable location = /Users/alexandrechouinard/workspace/repos/ops2.0/provisioning-prometheus-vm/venv/bin/ansible
  python version = 3.7.4 (default, Sep  7 2019, 18:27:02) [Clang 10.0.1 (clang-1001.0.46.4)]
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
ansible-config dump --only-changed

DEFAULT_REMOTE_USER(env: ANSIBLE_REMOTE_USER) = alexc
```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->
Mac OSX

##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->
1. Encrypt a string using STDIN
1. Input vault password 2 times
1. Type variable value
1. Input ctrl+d two times

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
```
ansible-vault encrypt_string --stdin-name 'variable'
New Vault password: 
Confirm New Vault password: 
Reading plaintext input from stdin. (ctrl-d to end input)
value
variable: !vault |
          $ANSIBLE_VAULT;1.1;AES256
          63393237383235396431646465663363663433366232623736633136313039626264663832333731
          6136373531393136656135343135393964393439633038610a313130336635366362316264343662
          32343834656337643338393430636533366131326166323934623834646335626639393835393762
          3530306336356336660a306366333839376364666561613736306261393966613035623763366564
          3636
Encryption successful
```

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->

<!--- Paste verbatim command output between quotes -->
```
ansible-vault encrypt_string --stdin-name 'variable'
New Vault password: 
Confirm New Vault password: 
Reading plaintext input from stdin. (ctrl-d to end input)
valuevariable: !vault |
          $ANSIBLE_VAULT;1.1;AES256
          63393237383235396431646465663363663433366232623736633136313039626264663832333731
          6136373531393136656135343135393964393439633038610a313130336635366362316264343662
          32343834656337643338393430636533366131326166323934623834646335626639393835393762
          3530306336356336660a306366333839376364666561613736306261393966613035623763366564
          3636
Encryption successful
```

''' can encrypt any structured data file used by Ansible.
    This can include *group_vars/* or *host_vars/* inventory variables,
    variables loaded by *include_vars* or *vars_files*, or variable files
    passed on the ansible-playbook command line with *-e @file.yml* or *-e @file.json*.
    Role variables and defaults are also included!
    Because Ansible tasks, handlers, and other objects are data, these can also be encrypted with vault.
    If you'd like to not expose what variables you are using, you can keep an individual task file entirely encrypted.
    '''
    FROM_STDIN = "stdin"
    FROM_ARGS = "the command line args"
    FROM_PROMPT = "the interactive prompt"
    def __init__(self, args):
        self.b_vault_pass = None
        self.b_new_vault_pass = None
        self.encrypt_string_read_stdin = False
        self.encrypt_secret = None
        self.encrypt_vault_id = None
        self.new_encrypt_secret = None
        self.new_encrypt_vault_id = None
        super(VaultCLI, self).__init__(args)
    def init_parser(self):