Secret key gen prepends, should overwrite

[Jim Menard]

When the "play secret" command generates a new secret key, it updates conf/application.conf with the new value. However, the new value does not replace the old, it is prepended. Example:

  $ grep 'application\.secret' conf/application.conf
  application.secret=OLD
  $ play secret
  ...
  ~ Keep the secret: NEW
  $ grep 'application\.secret' conf/application.conf
  application.secret=NEWOLD

The new value in the conf file should be, of course, just "NEW".

I don't think this is a security vulnerability at all, unless the code can't handle really long secret keys.