This will case `make update` to run everytime there is a successful
merge. This will include everytime the is a non no-op merge. This *will
not run* if:
1. There is no changes.
2. There is a conflict in the merge.
Additionally the make install set will now sym link the post-merge hook.
Autoload is used by vim.plug, but the makefile will pull fresh copy of
the vim.plug script on merge (after any non no-op pull).
Backup will keep. Well backups. Never check these in.
