can get stuck in infinite loop of requiring git-hub username and password. can be bypassed by giving login details as args to one liner.

[dg-shadow]

TASK [ros_workspace : Load /home/dg/workspaces/flexible/base dependencies just 1 level deep] ***
task path: /tmp/sr-build-tools/ansible/roles/ros_workspace/tasks/main.yml:84
<localhost> ESTABLISH LOCAL CONNECTION FOR USER: dg
<localhost> EXEC /bin/sh -c '( umask 77 && mkdir -p "` echo $HOME/.ansible/tmp/ansible-tmp-1473243763.32-21652578540870 `" && echo ansible-tmp-1473243763.32-21652578540870="` echo $HOME/.ansible/tmp/ansible-tmp-1473243763.32-21652578540870 `" ) && sleep 0'
<localhost> PUT /tmp/sr-build-tools/ansible/roles/ros_workspace/files/../files/load_repositories.sh TO /home/dg/.ansible/tmp/ansible-tmp-1473243763.32-21652578540870/load_repositories.sh
<localhost> EXEC /bin/sh -c 'chmod -R u+x /home/dg/.ansible/tmp/ansible-tmp-1473243763.32-21652578540870/ && sleep 0'
<localhost> EXEC /bin/sh -c 'LANG=en_GB.UTF-8 LC_ALL=en_GB.UTF-8 LC_MESSAGES=en_GB.UTF-8 /home/dg/.ansible/tmp/ansible-tmp-1473243763.32-21652578540870/load_repositories.sh /home/dg/workspaces/flexible/base/src /home/dg/workspaces/flexible/base/src 1 && sleep 0'
Username for 'https://github.com': Username for 'https://github.com': Username for 'https://github.com': Username for 'https://github.com': Username for 'https://github.com': 

Enter user name.

Password for 'https://username-entered@github.com':

Enter password.

Password for 'https://password-entered@github.com':

Then the last step repeats ad infinitum.

Discovered using one-liner given here