I get this error when I try to pull from remote repository using Egit team>pull
The current branch is not configured for pull No value for key branc
As it turns out, @Michał Szajbe's answer IS the solution to the problem. The eclipse keys in question are built from the egit "working directory". Should you encounter this problem, then find the .git directory in that working directory and edit the .git/config file with a text editor, adding the section Michal describes. This is in my experience a fairly standard operation these days for cases when you first git init and push to an uninitialized remote, that creates the master branch. I haven't found a way in that case not to do the manual editing in order to git pull, even with command line git.
After the edit is saved, right click on the git repo in your egit "Git Repositories" perspective, and choose properties, you will now see this section of keys has been created (or more likely just read from the config file) and a remote master to local master git pull will operate as expected going forward.

It's possible that you could enter these keys and values yourself, but copying and pasting what Michal shows is certainly a lot faster and probably safer. I didn't actually try adding the keys manually through the property editor nor am I likely to, as I know this method works, and makes sense since egit is simply calling through to the local git repo.
I am also supporting some people in my office who are using Flex and the Flexbuilder editor which is built on top of eclipse and egit. These instructions are equally relevant to them.