merge,diff: remove the_repository check before prefetching blobs

Prefetching of blobs from promisor remotes was added to diff in
7fbbcb2 (diff: batch fetching of missing blobs, 2019-04-05).  In
that commit,

  https://lore.kernel.org/git/20190405170934.20441-1-jonathantanmy@google.com/

was squashed into

  https://lore.kernel.org/git/44de02e584f449481e6fb00cf35d74adf0192e9d.1553895166.git.jonathantanmy@google.com/

without the extra explanation about the squashed changes being added to
the commit message; in particular, this explanation from that first link
is absent:

> Also, prefetch only if the repository being diffed is the_repository
> (because we do not support lazy fetching for any other repository
>  anyway).

Then, later, this checking was spread from diff.c to diffcore-rename.c
and diffcore-break.c by 95acf11 (diff: restrict when prefetching
occurs, 2020-04-07) and then further split in d331dd3
(diffcore-rename: allow different missing_object_cb functions,
2021-06-22).  I also copied the logic from prefetching blobs from
diff.c to merge-ort.c in 2bff554 (merge-ort: add prefetching for
content merges, 2021-06-22).

The reason for all these checks was noted above -- we only supported
lazy fetching for the_repository.  However, that changed with
ef830cc (promisor-remote: teach lazy-fetch in any repo,
2021-06-17), so these checks are now unnecessary.  Remove them.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: newren

diff.c

@@ -7176,7 +7176,7 @@ void diffcore_std(struct diff_options *options)
 	 * If no prefetching occurs, diffcore_rename() will prefetch if it
 	 * decides that it needs inexact rename detection.
 	 */
-	if (options->repo == the_repository && repo_has_promisor_remote(the_repository) &&
+	if (repo_has_promisor_remote(options->repo) &&
 	    (options->output_format & output_formats_to_prefetch ||
 	     options->pickaxe_opts & DIFF_PICKAXE_KINDS_MASK))
 		diff_queued_diff_prefetch(options->repo);

diffcore-break.c

@@ -69,7 +69,7 @@ static int should_break(struct repository *r,
 	    oideq(&src->oid, &dst->oid))
 		return 0; /* they are the same */
 
-	if (r == the_repository && repo_has_promisor_remote(the_repository)) {
+	if (repo_has_promisor_remote(r)) {
 		options.missing_object_cb = diff_queued_diff_prefetch;
 		options.missing_object_data = r;
 	}

diffcore-rename.c

@@ -987,7 +987,7 @@ static int find_basename_matches(struct diff_options *options,
 			strintmap_set(&dests, base, i);
 	}
 
-	if (options->repo == the_repository && repo_has_promisor_remote(the_repository)) {
+	if (repo_has_promisor_remote(options->repo)) {
 		dpf_options.missing_object_cb = basename_prefetch;
 		dpf_options.missing_object_data = &prefetch_options;
 	}
@@ -1574,7 +1574,7 @@ void diffcore_rename_extended(struct diff_options *options,
 
 	/* Finish setting up dpf_options */
 	prefetch_options.skip_unmodified = skip_unmodified;
-	if (options->repo == the_repository && repo_has_promisor_remote(the_repository)) {
+	if (repo_has_promisor_remote(options->repo)) {
 		dpf_options.missing_object_cb = inexact_prefetch;
 		dpf_options.missing_object_data = &prefetch_options;
 	}

merge-ort.c

@@ -4438,7 +4438,7 @@ static void prefetch_for_content_merges(struct merge_options *opt,
 	struct string_list_item *e;
 	struct oid_array to_fetch = OID_ARRAY_INIT;
 
-	if (opt->repo != the_repository || !repo_has_promisor_remote(the_repository))
+	if (!repo_has_promisor_remote(opt->repo))
 		return;
 
 	for (e = &plist->items[plist->nr-1]; e >= plist->items; --e) {