Merge branch 'ew/fetch-hiderefs'

A new "fetch.hideRefs" option can be used to exclude specified refs
from "rev-list --objects --stdin --not --all" traversal for
checking object connectivity, most useful when there are many
unrelated histories in a single repository.

* ew/fetch-hiderefs:
  fetch: support hideRefs to speed up connectivity checks

builtin/rev-list.c

@@ -39,7 +39,7 @@ static const char rev_list_usage[] =
 "    --tags\n"
 "    --remotes\n"
 "    --stdin\n"
-"    --exclude-hidden=[receive|uploadpack]\n"
+"    --exclude-hidden=[fetch|receive|uploadpack]\n"
 "    --quiet\n"
 "  ordering output:\n"
 "    --topo-order\n"