Git error “unable to locate xcodebuild” after a fresh OS X Mavericks upgrade

The error message error: refusing to update checked out branch: refs/heads/master is emitted by the remote repository and it means you're trying to push code to remote non-bare repository that has different code currently checked out in the working directory. The best way to avoid this problem is to push to bare repositories only - this problem cannot ever happen with a bare repository.

You can simply convert your remote repository to bare repository (there is no working copy in the bare repository - the folder contains only the actual repository data).

Execute the following command in your remote repository folder:

git config --bool core.bare true

Then delete all the files except .git in that folder. And then you will be able to perform git push to the remote repository without any errors.

Try cleaning-up your local repository with:

$ git gc --prune=now
$ git remote prune origin

man git-gc(1):

git-gc - Cleanup unnecessary files and optimize the local repository

git gc [--aggressive] [--auto] [--quiet] [--prune=<date> | --no-prune]

       Runs a number of housekeeping tasks within the current repository, such as compressing file revisions
       (to reduce disk space and increase performance) and removing unreachable objects which may have been
       created from prior invocations of git add.

       Users are encouraged to run this task on a regular basis within each repository to maintain good disk
       space utilization and good operating performance.

man git-remote(1):

git-remote - manage set of tracked repositories

git remote prune [-n | --dry-run] <name>

           Deletes all stale remote-tracking branches under <name>. These stale branches have already been
           removed from the remote repository referenced by <name>, but are still locally available in
           "remotes/<name>".