rm: ensure full index

Before iterating over all cache entries, ensure that a sparse index is
expanded to a full index to avoid unexpected behavior.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/rm.c

@@ -293,6 +293,8 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 
 	seen = xcalloc(pathspec.nr, 1);
 
+	/* TODO: audit for interaction with sparse-index. */
+	ensure_full_index(&the_index);
 	for (i = 0; i < active_nr; i++) {
 		const struct cache_entry *ce = active_cache[i];
 		if (!ce_path_match(&the_index, ce, &pathspec, seen))