unpack-trees: use repository from index instead of global

unpack_trees() currently initializes its repository from the
global 'the_repository', even though a repository instance is
already available via the source index.

Use 'o->src_index->repo' instead of the global variable,
reducing reliance on global repository state.

This is a step towards eliminating global repository usage in
unpack_trees().

Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Jayesh Daga <jayeshdaga99@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: jayesh0104

unpack-trees.c

@@ -1780,14 +1780,14 @@ static int clear_ce_flags(struct index_state *istate,
 
 	xsnprintf(label, sizeof(label), "clear_ce_flags(0x%08lx,0x%08lx)",
 		  (unsigned long)select_mask, (unsigned long)clear_mask);
-	trace2_region_enter("unpack_trees", label, the_repository);
+	trace2_region_enter("unpack_trees", label, istate->repo);
 	rval = clear_ce_flags_1(istate,
 				istate->cache,
 				istate->cache_nr,
 				&prefix,
 				select_mask, clear_mask,
 				pl, 0, 0);
-	trace2_region_leave("unpack_trees", label, the_repository);
+	trace2_region_leave("unpack_trees", label, istate->repo);
 
 	stop_progress(&istate->progress);
 	return rval;
@@ -1903,7 +1903,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 		BUG("o->df_conflict_entry is an output only field");
 
 	trace_performance_enter();
-	trace2_region_enter("unpack_trees", "unpack_trees", the_repository);
+	trace2_region_enter("unpack_trees", "unpack_trees", repo);
 
 	prepare_repo_settings(repo);
 	if (repo->settings.command_requires_full_index) {
@@ -2007,9 +2007,9 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 		}
 
 		trace_performance_enter();
-		trace2_region_enter("unpack_trees", "traverse_trees", the_repository);
+		trace2_region_enter("unpack_trees", "traverse_trees", repo);
 		ret = traverse_trees(o->src_index, len, t, &info);
-		trace2_region_leave("unpack_trees", "traverse_trees", the_repository);
+		trace2_region_leave("unpack_trees", "traverse_trees", repo);
 		trace_performance_leave("traverse_trees");
 		if (ret < 0)
 			goto return_failed;
@@ -2106,7 +2106,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 		dir_clear(o->internal.dir);
 		o->internal.dir = NULL;
 	}
-	trace2_region_leave("unpack_trees", "unpack_trees", the_repository);
+	trace2_region_leave("unpack_trees", "unpack_trees", repo);
 	trace_performance_leave("unpack_trees");
 	return ret;