Display success message if migration has no known problems
Display success message if migration has no known problems

This is a fairly fragile hack: the detection of a success case is
particularly sensitive to understanding of flow control of the main
gnarly multiphase loop (which has some code to deal with interrupts),
and use of the feed-forward infrastructure to propagate information.

Signed-off-by: Daniel Farina <3d0f3b9ddcacec30c4008c5e030e6c13a478cb4f@heroku.com>

heroku/heroku-pgmigrate