Merge branch 'mv/merge-custom'

* mv/merge-custom:
t7606: fix custom merge test
Fix "git-merge -s bogo" help text
Update .gitignore to ignore git-help
Builtin git-help.
builtin-help: always load_command_list() in cmd_help()
Add a second testcase for handling invalid strategies in git-merge
Add a new test for using a custom merge strategy
builtin-merge: allow using a custom strategy
builtin-help: make some internal functions available to other builtins

Conflicts:
help.c

diff --cc Makefile
Simple merge

diff --cc builtin-merge.c
Simple merge

diff --cc t/t7600-merge.sh
Simple merge