6d4bb3833c3d2114d (fetch: verify we have everything we need before updating our ref) breaks fetch

Hello,

Whilst trying to do some work related to fetch, I came across a regression in the 'next' branch. Bisecting gave me this commit as breaking point (and I tried with the parent and there it worked). When doing 'git fetch', rev-list will complain about usage, and fetch will say that we didn't receive enough, even though earlier versions of git have no problems. This fails both on github and on git.or.cz and for git and http transports:

$ ./git-fetch git://repo.or.cz/git
usage: git rev-list [OPTION] <commit-id>... [ -- paths... ]
  limiting output:
    --max-count=<n>
    --max-age=<epoch>
    --min-age=<epoch>
    --sparse
    --no-merges
    --min-parents=<n>
    --no-min-parents
    --max-parents=<n>
    --no-max-parents
    --remove-empty
    --all
    --branches
    --tags
    --remotes
    --stdin
    --quiet
  ordering output:
    --topo-order
    --date-order
    --reverse
  formatting output:
    --parents
    --children
    --objects | --objects-edge
    --unpacked
    --header | --pretty
    --abbrev=<n> | --no-abbrev
    --abbrev-commit
    --left-right
  special purpose:
    --bisect
    --bisect-vars
    --bisect-all
error: git://repo.or.cz/git did not send all necessary objects