git-fetch.txt says the following, whereas the only command that appears to use FETCH_HEAD in Git HEAD is git-pull.
| The ref names and their object names of fetched refs are stored | in `.git/FETCH_HEAD`. This information is left for a later merge | operation done by "git merge".
Maybe the latter sentence could be reworded as something like this ?
| This information is left for a later merge operation, for use by "git | pull" or other porcelain tools.
Best regards,
-- Yann.