Merge branch 'rc/fetch-refetch'

"git fetch --refetch" learned to fetch everything without telling
the other side what we already have, which is useful when you
cannot trust what you have in the local object store.

* rc/fetch-refetch:
  docs: mention --refetch fetch option
  fetch: after refetch, encourage auto gc repacking
  t5615-partial-clone: add test for fetch --refetch
  fetch: add --refetch option
  builtin/fetch-pack: add --refetch option
  fetch-pack: add refetch
  fetch-negotiator: add specific noop initializer

Documentation/technical/partial-clone.txt

@@ -181,6 +181,9 @@ Fetching Missing Objects
   currently fetches all objects referred to by the requested objects, even
   though they are not necessary.
 
+- Fetching with `--refetch` will request a complete new filtered packfile from
+  the remote, which can be used to change a filter without needing to
+  dynamically fetch missing objects.
 
 Using many promisor remotes
 ---------------------------