contrib/gcc_update does not work

[Uros Bizjak <ubizjak at gmail dot com>]

gcc_update, when called from newly initialized and pulled tree does not work:

--cut here--
$ contrib/gcc_update
Updating GIT tree
There is no tracking information for the current branch.
Please specify which branch you want to rebase against.
See git-pull(1) for details.

    git pull <remote> <branch>

If you wish to set tracking information for this branch you can do so with:

    git branch --set-upstream-to=origin/<branch> master

Adjusting file timestamps
git pull of full tree failed.
--cut here--

I would also appreciate a simple step-by step instructions on how to
set-up the local repo and basic workflow with git for "non-power"
users, as was the case with now obsolete instructions for anonymous
SVN r/o access [1] and r/w access [2]. Basically, push-my-first-patch
example.

[1] https://gcc.gnu.org/svn.html
[2] https://gcc.gnu.org/svnwrite.html

Thanks,
Uros.