"Entry not saved" text doesn't appear in default stdin editor

[micahellison]

Bug Report

Environment

• jrnl --diagnostic output:

jrnl: v2.8.4-beta2
Python: 3.8.2 (tags/v3.8.2:7b3ab59, Feb 25 2020, 23:03:10) [MSC v.1916 64 bit (AMD64)]
OS: Windows 10

• Install method: pipx

Current Behavior

When you use the default editor (stdin) and enter nothing then press Ctrl+Z (or Ctrl+D on *nix), there's no message. However, when you use a configured editor and enter nothing then close it, it says "[Nothing saved to file]".

Expected Behavior

The user should see the same message for both input methods when nothing is saved to the journal.

Repro Steps

• Ensure your config file editor key is blank
• Type jrnl
• Hit Ctrl+Z on Windows or Ctrl+D on *nix

Other Information

A resolution should have:

• A message indicating nothing was saved when the user doesn't enter anything using the default editor
• A BDD test that confirms that the message appears in this situation