Merge branch 'mm/pull-upload-pack' into maint

"git pull" in recent releases of Git has a regression in the code
that allows custom path to the --upload-pack=<program>.  This has
been corrected.

Note that this is irrelevant for 'master' with "git pull" rewritten
in C.

* mm/pull-upload-pack:
  pull: pass upload_pack only when it was given
  pull.sh: quote $upload_pack when passing it to git-fetch

git-pull.sh

@@ -295,7 +295,7 @@ test true = "$rebase" && {
 }
 orig_head=$(git rev-parse -q --verify HEAD)
 git fetch $verbosity $progress $dry_run $recurse_submodules $all $append \
-$upload_pack $force $tags $prune $keep $depth $unshallow $update_shallow \
+${upload_pack:+"$upload_pack"} $force $tags $prune $keep $depth $unshallow $update_shallow \
 $refmap --update-head-ok "$@" || exit 1
 test -z "$dry_run" || exit 0