Now that JENKINS-33599 changed the password to be written to a file, it would be more convenient for copy-pasting if the password was printed on its own line — i.e. the file should end with a (platform-specific) newline character.

With the 2.0 beta, I saw this:

chris@rebigulator:~$ cat /tmp/j2beta/secrets/initialAdminPassword
c84b4a5991db49ef9d431159421107bdchris@rebigulator:~$

The setup wizard unlock field has been changed to a password field, so that also didn't help me in seeing that I had made a mistake in copying the password.

Here the password is just written straight to the file:
https://github.com/jenkinsci/jenkins/blob/1735f3c/core/src/main/java/jenkins/install/SetupWizard.java#L64