Merge branch 'fc/advice-diverged-history'

After "git pull" that is configured with pull.rebase=false
merge.ff=only fails due to our end having our own development, give
advice messages to get out of the "Not possible to fast-forward"
state.

* fc/advice-diverged-history:
  advice: add diverging advice for novices

diff --cc advice.c
Simple merge

diff --cc advice.h
Simple merge