Merge branch 'tr/maint-show-walk' into maint

"git show"'s auto-walking behaviour was an unreliable and
unpredictable hack; it now behaves just like "git log" does when it
walks.

* tr/maint-show-walk:
show: fix "range implies walking"
Demonstrate git-show is broken with ranges

diff --cc builtin/log.c
Simple merge