bundle-uri: copy all bundle references ino the refs/bundle space

When downloading bundles via the bundle-uri functionality, we only copy the
references from refs/heads into the refs/bundle space. I'm not sure why this
refspec is hardcoded to be so limited, but it makes the ref negotiation on
the subsequent fetch suboptimal, since it won't use objects that are
referenced outside of the current heads of the bundled repository.

This change to copy everything in refs/ in the bundle to refs/bundles/
significantly helps the subsequent fetch, since nearly all the references
are now included in the negotiation.

The update to the bundle-uri unbundling refspec puts all the heads from a
bundle file into refs/bundle/heads instead of directly into refs/bundle/ so
the tests also need to be updated to look in the new heirarchy.

Signed-off-by: Scott Chacon <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: schacon

Documentation/technical/bundle-uri.adoc

@@ -232,13 +232,13 @@ will interact with bundle URIs according to the following flow:
    are present in the client repository. If some are missing, then the
    client delays unbundling until other bundles have been unbundled,
    making those OIDs present. When all required OIDs are present, the
-   client unbundles that data using a refspec. The default refspec is
-   `+refs/heads/*:refs/bundles/*`, but this can be configured. These refs
-   are stored so that later `git fetch` negotiations can communicate each
-   bundled ref as a `have`, reducing the size of the fetch over the Git
-   protocol. To allow pruning refs from this ref namespace, Git may
-   introduce a numbered namespace (such as `refs/bundles/<i>/*`) such that
-   stale bundle refs can be deleted.
+   client unbundles that data using a refspec. The refspec used is
+   `+refs/*:refs/bundles/*`. These refs are stored so that later
+   `git fetch` negotiations can communicate each bundled ref as a `have`,
+   reducing the size of the fetch over the Git protocol. To allow pruning
+   refs from this ref namespace, Git may introduce a numbered namespace
+   (such as `refs/bundles/<i>/*`) such that stale bundle refs can be
+   deleted.
 
 3. If the file is instead a bundle list, then the client inspects the
    `bundle.mode` to see if the list is of the `all` or `any` form.

bundle-uri.c

@@ -403,7 +403,7 @@ static int unbundle_from_file(struct repository *r, const char *file)
 		const char *branch_name;
 		int has_old;
 
-		if (!skip_prefix(refname->string, "refs/heads/", &branch_name))
+		if (!skip_prefix(refname->string, "refs/", &branch_name))
 			continue;
 
 		strbuf_setlen(&bundle_ref, bundle_prefix_len);