Few things irritate me more than poorly documented dependencies. If your tool or software documentation states you can install your widget with one command and it does not work you are probably annoying people.
Consider this a running list of tools and their often not well documented dependency chains. Feel free to chime in with your examples in the comments.
Ansible is one of my favorite tools has many installation options. I tend to need the latest features so I end up using pip to install Ansible. On CentOS 7 and Red Hat 7 the Ansible dependency chain has been growing lately:
sudo yum install gcc libffi-devel openssl-devel python-devel python-setuptools
Once you install these dependencies you can run the following error free:
sudo easy_install pip && sudo pip install -U setuptools &&