old_contents: from django import template
  register = template.Library()
  
  with open(".git/refs/heads/master") as fh:
      GIT_REVISION = fh.read().decode("utf8") or "unknown"
  
  @register.simple_tag
  def git_revision():
      return GIT_REVISION
  
new_contents: import os
  from django import template
  from django.conf import settings
  register = template.Library()
  
  with open(os.path.join(settings.BASE_DIR, ".git", "refs", "heads", "master")) as fh:
      GIT_REVISION = fh.read().decode("utf8") or "unknown"
  
  @register.simple_tag
  def git_revision():
      return GIT_REVISION
  
subject: access proper .git directory