Documentation/fetch-options.txt

   1 -a, \--append::
   2         Append ref names and object names of fetched refs to the
   3         existing contents of `.git/FETCH_HEAD`.  Without this
   4         option old data in `.git/FETCH_HEAD` will be overwritten.
   5
   6 -f, \--force::
   7
   8 -t, \--tags::
   9         By default, the git core utilities will not fetch and store
  10         tags under the same name as the remote repository;  ask it
  11         to do so using `--tags`.  Using this option will bound the
  12         list of objects pulled to the remote tags.  Commits in branches
  13         beyond the tags will be ignored.
  14
  15 -u, \--update-head-ok::
  16         By default `git-fetch` refuses to update the head which
  17         corresponds to the current branch.  This flag disables the
  18         check.  Note that fetching into the current branch will not
  19         update the index and working directory, so use it with care.