Q:

How to update the repository with unaccepted pull requests?

The common circumstance is like this: in the github.com, we could fork another developing repository into our own account and continue the development with our own ideas. But meanwhile, the original repository we forked would also be alive thus have many pull requests. So, how could we  git pull these pull requests, which hadn't been accepted into the dev branch by the main contributor of the original repository, into our local repository?
UPDATED

A:

With a script, you could:

list the pull request of the upstream (original) repo (as in "How can I get a list of all pull requests for a repo through the github API?")
check if the PR is accepted or not (easier then checking the events)

From there, you can get the url of the fork repos (head repo), add them as remote, fetch them, merge the branch of the PR (the head.branch)

