[Buildbot-devel] MailNotifier customization, again

[Ian Zimmerman]

the new interface with messageFormatter and defaultMessage is an
improvement, but ...

defaultMessage should be a standalone function, not a method of
MailNotifier.  Note that self is not used anywhere in defaultMessage,
and since messageFormatter doesn't get a MailNotifier argument,
it is not possible to "subclass" defaultMessage from my
custom messageFormatter, so I have to copy & paste.

i