git-use-branch-if-already-there

#! /bin/bash

# Checkout input branch if it matches the current commit
#
# Useful to ensure submodules are using a branch (since they're usually at the
# same commit as master, but the branch isn't automatically checked out).

f() {
    branch=$1
    if [ -z "$branch" ] ; then
        echo "Branch to manage required."
        echo "Usage: $(basename $0) branch-name"
        exit -1
    fi

    n_commits=$(git show --oneline --no-patch $branch HEAD 2> /dev/null | wc -l)
    if [ $n_commits -eq 1 ] ; then
        git checkout $branch
    else
        git branch
    fi
}

f $*