While handy, "git_path()" is a dangerous function to use as a
callsite that uses it safely one day can be broken by changes
to other code that calls it.  Reduction of its use continues.

* jk/war-on-git-path:
  am: drop "dir" parameter from am_state_init
  replace strbuf_addstr(git_path()) with git_path_buf()
  replace xstrdup(git_path(...)) with git_pathdup(...)
  use git_path_* helper functions
  branch: add edit_description() helper
  bisect: add git_path_bisect_terms helper