Configure the repository to track correct branch of a submodule
Configure the repository to track correct branch of a submodule

The git repository of submodule submodules/spam_lists_lib has been in
a detached HEAD state. This commit fixes that by configuring the parent
repository to track branch 'master' of the submodule.

The solution is being taken from this answer:
http://stackoverflow.com/a/36375256/5069081

piotr-rusin/url-shortener,piotr-rusin/url-shortener