sync between independent git repo

A = PROJECT/vendor/plugins/PLUGIN
B = PLUGIN_main_repository

A> git whatchanged .piston.yml
# find last commit for .piston.yml
A> git format-patch COMMIT --relative .
A> cd B
B> git am A/*.patch

if we can't use git submodule

# check if everything is ok
> colordiff -r A B | less --raw