parameters: (filename)
docstring: Given a filename of a .git/HEAD file return ref path.
  
    In particular, if git is in detached head state, this will
    return None. If git is in attached head, it will return
    the branch reference. E.g. if on 'master', the HEAD will
    contain 'ref: refs/heads/master' so 'refs/heads/master'
    will be returned.
  
    Example: parse_branch_ref(".git/HEAD")
    Args:
      filename: file to treat as a git HEAD file
    Returns:
      None if detached head, otherwise ref subpath
    Raises:
      RuntimeError: if the HEAD file is unparseable.
docstring_summary: Given a filename of a .git/HEAD file return ref path.
docstring_tokens: Given a filename of a . git / HEAD file return ref path .
function: def parse_branch_ref(filename):
    """Given a filename of a .git/HEAD file return ref path.
  
    In particular, if git is in detached head state, this will
    return None. If git is in attached head, it will return
    the branch reference. E.g. if on 'master', the HEAD will
    contain 'ref: refs/heads/master' so 'refs/heads/master'
    will be returned.
  
    Example: parse_branch_ref(".git/HEAD")
    Args:
      filename: file to treat as a git HEAD file
    Returns:
      None if detached head, otherwise ref subpath
    Raises:
      RuntimeError: if the HEAD file is unparseable.
    """
  
    data = open(filename).read().strip()
    items = data.split(" ")
    if len(items) == 1:
      return None
    elif len(items) == 2 and items[0] == "ref:":
      return items[1].strip()
    else:
      raise RuntimeError("Git directory has unparseable HEAD")
function_tokens: def parse_branch_ref ( filename ) : data = open ( filename ) . read ( ) . strip ( ) items = data . split ( " " ) if len ( items ) == 1 : return None elif len ( items ) == 2 and items [ 0 ] == "ref:" : return items [ 1 ] . strip ( ) else : raise RuntimeError ( "Git directory has unparseable HEAD" )